The Imperious Leader is the highest authority of the Cylon Empire. There is only one Imperious Leader, although there are others to replace it should the Cylon succumb to destruction. Typically, their potential replacements are called IL-series Cylons, and are typically the politicians or viceroys of the Cylon Empire.
In the original novelization, the Imperious Leader had six brains, all capable of independent or collective, unified thought.
Imperious Leaders are also programmed, each one an improvement on the previous generation. In the epilogue of "Saga of a Star World," the Imperious Leader tells Baltar that his predecessor was programmed in a time when Cylons were less tolerant.
The origin of the Imperious Leader can be traced directly to Count Iblis. In "War of the Gods, Part II," Baltar tells Iblis that he recognizes his voice as that of the Cylon Imperious Leader. Iblis balks at this, replying that he would have to be 1,000 yahrens old since the Cylon race is just as old.
A green lizard can be seen sitting on the shoulder of the Imperious Leader in the pilot episode. This reptilian/lizard reference was never fully explored in the Original Series run, except during a scene on Carillon where Apollo explains the origins of the Cylons to Boxey.
Biography
The Imperious Leader visits Gamoray.
The Imperious Leader strikes a bargain with Baltar, allowing the Cylons to take control of the Twelve Colonies but leaving Baltar's colony alone (with Baltar in command). When the plan comes to fruition, the Imperious Leader renegotiates the bargain and destroys Baltar's colony as well. Baltar is thanked and sentenced to a public execution. The Imperious Leader is present at the Battle of Carillon and is killed when his basestar is too close to the planet Carillon when the planet explodes (Saga of a Star World).
The next Imperious Leader is more tolerant, and commutes Baltar's death sentence. Baltar is given command of a basestar, and the assistance of Lucifer in the hope of tracking down the Colonial Fleet and extending an offer of peace from the Cylon's new regime (Lost Planet of the Gods, Part I).
The Imperious Leader is last seen visiting the planet Gamoray, where he dedicates a Cylon cultural center. The Imperious Leader is present at the Cylon compound when a commando unit disables the planetary defense systems, allowing Vipers to attack freely. It is unknown whether this Imperious Leader survives the Battle of Gamoray (The Living Legend, Part II).
