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The term "Final Five" collectively describes five of the twelve Cylon humanoid models, namely Samuel Anders, Tory Foster, Ellen Tigh, Saul Tigh, and Galen Tyrol, whose identities were lost to the majority of the Cylon populace. These five Cylons are the descendants of the Thirteenth Tribe, ancient humanoid artificial life forms created by humans on Kobol thousands of years ago. They are also the creators of the so-called Significant Seven Cylons, plus Number Seven, whose entire line was wiped out. Although they actually pre-date the others, they are referred to as the "Final Five" because they were the last five humanoid Cylon models to be revealed; the term was coined by Gaius Baltar. They are also referred to simply as "the Five".
Downloaded Three, whom Gaius Baltar calls by her sister's alias, D'Anna Biers, repeatedly commits suicide to get glimpses of five white-cloaked beings that she believes are images of the Final Five. She attempts to draw what she has seen, but has difficulty in doing so (Hero).
One detailed sketch which she briefly shows to Baltar depicts her personal artistic rendering of the faces of the Five (The Passage). The sketch is meant to depict Saul Tigh, Ellen Tigh, Galen Tyrol, Samuel Anders, and Tory Foster. (Crossroads, Part II, Sometimes a Great Notion).
Baltar's ability to see a virtual doppelganger of Caprica-Six (as well as enjoying her company in various pleasant environments) leads him to suggest that he might be using a Cylon technique known as projection. This suspicion, in turn, makes Baltar begin a personal inquiry into his own nature after allying himself with D'Anna-Three.
The two eventually make their way to the algae planet, where a Colonial structure, the fabled Temple of Five, awaits with possible answers ("The Passage", "The Eye of Jupiter"). When the system's dying star goes nova, a ray of light is generated by the mechanisms of the temple. Number Three steps into the light and suddenly finds herself back in the Opera House and before the same image of the Five, not persistent. Upon seeing their faces she recognizes one of them in particular, saying in surprise "You... forgive me... I had no idea." She is then pulled back to reality and collapses in Baltar's arms, apparently suffering the effects of a brain hemorrhage. She tells Baltar, "You were right," but dies before answering about what, or telling him what she saw. She tells the Cavil who boxes her upon her resurrection that there are five other Cylons, and he will see them some day (Rapture), unaware that he already knows what they look like (No Exit).
Later, she shows that she is aware of the identities of the four revealed Cylons, but does not immediately identify Ellen Tigh, the fifth, as Ellen is not among the population of the Colonial Fleet and is believed to be dead (Revelations, Sometimes a Great Notion). Unbeknownst to everyone at that time, Ellen survived her husband killing her by downloading into a new body on a Resurrection Ship and has been a secret prisoner of Cavil since the Battle of New Caprica.
Awareness of the Five by the other seven Cylons
Caprica-Six indicates that the Cylons do not speak of the Five, but she knows how many there are. She later tells Roslin that she is actually "programmed not to think of them." Downloaded Three also indicates to Baltar that they do not discuss the Five. A Cavil realizes in the Temple of Five that the Three is attempting to see the Final Five, and not simply seeking Earth. He tells her "That can't happen" and points a gun at her to stop her, but is shot by Baltar. Later, a Cavil explains that because of her obsession her entire line will be boxed (Rapture).
A Leoben Conoy claims that "Adama is a Cylon", although, even if he were one, Conoy should not know this. While there is a slight possibility that he could be referring to Adama's sister, it is commonly believed that he is lying in order to create mistrust (Flesh and Bone).
The Boomer copy of Number Eight, interrogated by Baltar, declares there are eight Cylons in the Fleet. Given that these Seven do not interact (or are unwilling to interact) with the Five at the time, the number that Boomer gives is likely other copies of the Seven in disguise. (This would account for Aaron Doral, Shelly Godfrey, Simon O'Neill, D'Anna Biers, Brother John Cavil, Leoben Conoy, a prostitute Six, and herself, who are or were in the fleet at the time). Also supporting this is the scene where number Three and Sharon Valerii discover Samuel Anders and refer to him as human in the episode "Downloaded". A later episode, "Rapture", shows a Three recognizing a putative human among the faces of the Five, confirming the lack of information to the Seven on the Five's identities.
Both Caprica Six and Sharon Agathon share a dream vision in which the glowing, white-robed figures of the Five are shown in the Opera House (Crossroads, Part II). After their activation, Caprica-Six, aboard Galactica, has a sense that the Final Five are near (He That Believeth In Me), but fails to recognize Tigh even when directly confronted by him (Escape Velocity).
There are cases of the Seven and the Five committing violence on each other, including:
While Centurions are programmed to recognize and obey humanoid Cylons, on a number of occasions they shoot at members of the Five, prior to their activation, including Tyrol on both Kobol and on the algae planet, Anders both on Caprica and outside the Temple of Five, and most members during the escape from New Caprica. The behavior of a Centurion present at Ellen Tigh's resurrection indicates that its programming requires it to keep her prisoner for Cavil.
During the Battle of the Ionian Nebula, a Cylon Raider makes eye contact with Anders in a Viper, causing a brief red flash from Anders' eye. Immediately, the Raider breaks off its attack, and the entire Cylon fleet retreats (He That Believeth In Me), after responding this IFF procedure. However, this display of free will and the prospect of making contact with the Five, creates a schism between the other six Cylons, who violently disagree over the appropriate course of action (Six of One).
Downloaded Three is unboxed by the Ones, to ostensibly convince the rebels to stop fighting further, and rescued by the human-Cylon alliance, after killing Cavil. She initially keeps her knowledge about the Five's identities a secret in an attempt to secure her safety should the alliance collapse (The Hub). When she resumes her position as the de facto leader of the Cylon rebels she reveals to President Roslin and Admiral Adama that there are only four Cylons in their fleet, and does not elaborate on the status of the fifth, believing, as the Colonials also did at the time, that Ellen has been dead for over a year not knowing she'd survived by downloading into a new body and resurrecting. She then holds the humans aboard her basestar, including Roslin and Gaius Baltar, hostage in an attempt to force the four out of hiding. Tory Foster willingly goes to the basestar, and Three introduces her to her new Cylon "brothers" and "sisters". In the ensuing stand off, President Lee Adama attempts to force her to release her hostages by threatening to execute Tigh, Tyrol, and Anders and in doing so publicly announces their identities to the other Cylons on the basestar (Revelations).
In No Exit, it is revealed that Cavil has always known the identities of the Final Five. Cavil revealed Ellen's identity to Boomer two months prior to the events in The Eye of Jupiter and Rapture, the Fours are also aware of Ellen's identity in the main timeframe of No Exit; it is unclear when they became aware of this, or whether the Fives are also aware.
Four revealed, and their nature
As the Fleet draws closer to the Ionian nebula, four people begin hearing an unusual melody: these four are Colonel Saul Tigh, Chief Galen Tyrol, Ensign Samuel Anders and presidential aide Tory Foster (Crossroads, Part I). Tyrol and Anders say that the song seems like something from their childhoods, while Tigh becomes progressively more disturbed as he begins to hear the music everywhere on Galactica. Foster becomes noticeably distracted, irritable, and unkempt, claiming to have not been sleeping well. When the fleet finally arrives at the Ionian Nebula the song becomes clear to the four who can hear it and they begin to stalk the halls of Galactica muttering its mysterious lyrics. Eventually, the four arrive at Galactica’s gym and upon seeing each other the truth becomes clear to them; they are Cylons, four of the Final Five. When they learn the truth, they decide to remain loyal to the Colonial Fleet, because they thought they were humans for as long as they can remember, and cling to what they know to make sense of their lives. Moreover, Tigh sees himself as a soldier first and wants to hold up his oath.
After activation, the four revealed Cylons are unaware of any thoughts like Boomer's Cylon directives other than that they are Cylons. In a sense they know less than the audience and the Significant Seven, who at least know that the Final Five are fundamentally different models. Tigh and Anders painfully and confusedly recite events from their lives which make little sense in the context of their newly revealed nature. With particular pain, Tigh asks "My gods, what about Ellen?" His personal execution of his wife for being a Cylon collaborator, and his pain over it, has been a major theme in the episode. It is revealed much later that Ellen Tigh was in fact the fifth member of the final five and that she and the other four once lived on Original Earth two millenia prior to the First Cylon War.
The nature of these Cylons is clearly different from the other seven. In particular, Colonel Tigh's friendship with William Adama stretches back a long time, though not to the first Cylon War itself (Scattered, Crossroads, Part II)
These Cylons possess superhuman physical strength, like the Significant Seven models (The Ties That Bind, Escape Velocity). Also, Galen Tyrol was less affected than his wife by decompression sickness (A Day in the Life). During the Battle of the Ionian Nebula, Samuel Anders' right eye responded to a Cylon Raider's scan by flashing red (He That Believeth In Me). The Final Five are capable of projection, of identifying Significant Seven copies by sight, and of being connected to a Cylon datastream (Deadlock, Someone to Watch Over Me, Islanded in a Stream of Stars).
When Downloaded Three takes control of the rebel Cylon baseship, she holds humans ransom, demanding the Colonials permit the remaining four Final Five Cylons to join her. She is aware that one Final Five member is no longer among the fleet. Although civilian Tory Foster flies to the baseship under the pretext of taking medication to the captive President, the three soldiers remain loyal to the Colonies. To change Three's equasion, Tigh admits his nature and presents himself for arrest. Waiting in an airlock for Three to capitulate, he identifies Anders and Tyrol to Acting President Lee Adama who has the two aprehended and brought to the airlock. In conjunction with the resulting alliance between Colonials and the rebel Cylons, Acting President Adama pardons all Cylons and releases them from custody. (Revelations)
Though freed by Lee Adama, neither Tigh, Anders nor Tyrol wears rank insignia on his fatigue collars while surveying post-apocalyptic Original Earth and upon their return to Galactica. ("Revelations", "Sometimes a Great Notion"). Anders, however, continues to wear insignia on his flight suit under his fatigue field jacket. Conversely, the human soldiers and Lt. Sharon Agathon wear their rank on their fatigues. Tigh continues to reside in his quarters and his sidearm has not been confiscated, but he is not shown to have resumed his rank and duties until the morning after Admiral Adama's drunken attempt to motivate Tigh to kill him. (Sometimes a Great Notion).
The Final Five do not appear have reproductive difficulties as severe as those of the Seven. So far one of Final Five, Saul Tigh, has managed to sire progeny. Only two of the millions of Significant Seven copies: Sharon Agathon and Caprica-Six, have managed to become pregnant, and none of the countless male Significant Seven copies have sired children. All attempts by the Tighs to have children between themselves, however, failed during Ellen's presumably fertile years.
The Fifth is revealed
On the devastated Earth the Four have visions that confirm their origin, that had indeed lived there 2,000 years ago as part of the Thirteenth Tribe, a humanoid Cylon civilization, all killed in the nuclear holocaust. Unknown to any of them is how they all found themselves as Colonials in a star system light-years away, their memories of their past lives all but gone.
Wading in the dead waters of Earth shortly before the Fleet returns to space and an unknown future, Colonel Tigh stumbles upon a post box hatch. Handling the hatch, he experiences a vision of his short moments in the holocaust, hearing shouts from a woman trapped in the fallen debris of an apartment building. The face is unmistakable. The memory of Ellen Tigh tells him that "Everything is in place," that they all will be reborn again, together. In that instant, Saul Tigh realizes that his late wife is the last of the Final Five Cylons (Sometimes a Great Notion).
Tigh informs only the "upper echelons" of Ellen's true nature, including Admiral William Adama, former interim President Lee Adama, Vice President Tom Zarek, and President Laura Roslin. At a press conference on Colonial One, Lee Adama informs the press, inadvertently, that the final Cylon is both a woman and believed to be dead, though he does not specifically identify Ellen by name (A Disquiet Follows My Soul).
Ellen's true nature is later made public knowledge upon her return to the fleet (Deadlock).
The story of the Final Five
Finaly, the origin of the Five is revealed (TRS: "No Exit"). Samuel Anders regains his Cylon memories after getting shot in the head and he reveals what he knows to Saul Tigh, Galen Tyrol, and Tory Foster, as well as Kara Thrace. The Final Five worked in a research facility on Earth. Saul and Ellen were married even back then and Tyrol and Foster were in love and planned to get married. What they were researching was a way to re-invent resurrection technology. Organic memory transfer came from Kobol, but had fallen out of use after the Thirteenth Tribe Cylons started to procreate. The Five worked night and day to rebuild it, spurred by apocalyptic warnings from the Messengers. Tyrol's work on the project was "amazing", but it was Ellen who made the intuitive leap that brought the system back online.
The Five then placed the technology and new bodies for them on a ship they placed in orbit around Earth. When they were all killed in the nuclear holocaust unleashed by Earth's mistreated mechanical Cylons, they were reborn in their new bodies on the ship in orbit. Realizing that the other Twelve Tribes would continue to create artificial life, they headed for the Colonies to tell the humans to treat their creations well and keep them close. Because their people hadn't developed jump drives, the Five's ship traveled at relativistic, but subluminal speed. Time slowed down for them, but thousands of years had passed. According to Ellen, they stopped at the Temple of Hopes on their way to the Colonies, a temple that was created by their ancestors where they prayed and got a sign that led them to Earth. But Ellen said that the Five were not responsible for the vision that Number Three received of them, saying that it must have been orchestrated by God (TRS: "No Exit").
At some point between 58 and 53 years before the destruction of the Colonies, the Five may have been in contact with Zoe-A, the first Cylon created in the Twelve Colonies, via Caprica's Virtual world (CAP: DVD commentary for "Apotheosis").
By the time they got to the Colonies, the humans were already at war with the Centurions. The Centurions were already trying to make flesh bodies. They had created the Hybrids, but nothing that lived on its own, so the Five made a deal with them: they stop the war and the Five will help them create humanoid Cylons. The Centurions agreed and signed the Cimtar Peace Accord with humanity. The Five and the Centurions then withdrew to a mobile space station called The Colony placed beyond the Armistice Line. The Five and the Centurions apparently worked well together; the Five had learned to respect mechanical Cylons, and even adopted the Centurions' monotheistic beliefs (TRS: "No Exit").
The Five developed the eight humanoid models and gave them resurrection technology. They created Number One first, named him John. He was named after Ellen's father and also made in his image. Number One later changed his name to Cavil as he hated the name John. Cavil helped the Five build the other seven humanoid models. Ellen was close to Number Seven (Daniel) and Cavil, out of jealousy, contaminated the amniotic fluid in which the Daniel copies were maturing and then corrupted the genetic formula. This wiped out the copies permanently, and as Anders said of Daniel: "he died", indicating that the original Daniel was lost as well (TRS: "No Exit").
Cavil rejected mercy. He had a twisted idea of morality and despised the Five for contaminating their creations with human weaknesses and Centurion religious ideals, so he turned on them. He trapped them in a compartment and then he took the oxygen offline. Cavil boxed the Five at first but ultimately unboxed them and downloaded them into new bodies, blocking their true memories and implanting false ones, then introducing them one by one into the colonies. He introduced Saul first, not long after the war. And then Ellen. Cavil put the Five into the human population in order to truly show them what humans are like. He hoped that when they died and resurrected (which restores their real memories) they'd be ready to admit they were wrong. This is why they never knew who they really were (TRS: "No Exit"). The truth behind the music that triggered their knowledge of their true selves has yet to be revealed.
Cavil erased all knowledge of their identities from his siblings and his was the only Cylon model that knew their identities afterwards, but he kept at least one new body for each of them to download into. When Ellen was killed by Saul, she downloaded into a new body on a Resurrection Ship. With the destruction of the Hub, the Five are the only ones who know how to rebuild resurrection technology, but Ellen claims it would take all five working together to rebuild it and even then she's not sure they could do it (TRS: "No Exit").
When the attack on the Twelve Colonies happened, the Cavils prepared a new body for each of them aboard a Resurrection Ship sure that they couldn't survive what was coming and sure that they would download, regain their true memories and apologize for their views on the humans. When the attacks came, the Five managed to survive without dying and downloading to new bodies: Tyrol and Saul Tigh were aboard Galactica, Anders was in the mountains on Caprica doing some high-altitude survival training, there was a Simon there, but he was unaware of Anders' true nature, Tory was driving down a road in Delphi and was hit by a nuclear shockwave, but survived as her car protected her enough although she was injured and Ellen was in a bar on Picon with Cavil when it was hit by a nuclear shockwave. The bar was destroyed and Ellen severly injured, however she survived and Cavil kept her that way as he felt she hadn't learned her lesson and still needed to. Cavil then personally escorted her onto a rescue Raptor and to the Rising Star before planting himself as a clergyman on Galactica. Another Cavil infiltrated Samuel Anders resistance movement and delayed relaying the location to the other Cylons to see if Anders had changed. Anders hadn't, but his views on humanity changed the Cavil, who was presumably boxed eventually for his beliefs (TRS: "The Plan").
The Five Reunited
After Boomer helps Ellen escape from Cavil, the Five are finally reunited although Anders is pretty much brain dead except when he acts as a Hybrid for Galactica. The Rebel Cylons decide that perhaps they should leave the Fleet for good now that they have all of the Five and leave it up to the Five to decide. Saul and Anders vote no, Tory and Tyrol vote yes and initaly Ellen is undecided. In order to spite her husband as she's angry at him for his relationship with Caprica Six and Caprica's pregnancy by him, she votes yes, but after Caprica Six miscarries, she changes her mind saying that humans and Cylons should be together and she only voted yes out of anger. Ellen, Saul, and Tory later gather in Joe's Bar and are shocked to hear The Music played by Kara Thrace. When Admiral Adama calls everyone to talk about the rescue mission for Hera Agathon, Ellen tells Tory they're both going, and although Tory initaly protests, Tyrol convinces her to go and all of the Final Five go on the rescue. Anders acts as Galactica's Hybrid on the mission while Ellen and Tory and monitor him. Tyrol and Saul later join them to put out a fire. When the Opera House Prophecy finally comes true, the Five are standing in similar places on CIC's balcony to their positions in the Opera House balcony of the dream. The Five offer to give Cavil back Resurrection if he agrees to let them take Hera and leave humanity alone forever. He agrees, and, using the datastream in Anders' tank, they combine the keys to Resurrection technology in their minds and start transmitting to the Colony, but a side-effect is that they see each other's memories at the same time. Tyrol learns from Foster's memories that she murdered Cally and he flies into a rage, breaks the Five's download to the Colony and strangles Foster and breaks her neck, killing her. Later, the people of the Fleet have Anders fly Galactica and the other ships into the Sun, destroying the ships and himself. With the deaths of Anders and Foster, there are only three of the Final Five left alive, and there is little chance for Resurrection to be rebuilt as each of the Five had exclusive knowledge of some aspect of the technology.
Connections between the Colonial gods and Cylon God
Kara Thrace, The Eye of Jupiter, and the first Hybrid