The Gemini is an FTL-capable freighter in the Fleet which Sharon "Boomer" Valerii escorts to Laura Roslin's convoy of stranded ships during the Cylon attack. According to Lee Adama, the ship is a tylium refinery ship, and its presence is well appreciated since many of the ships in the convoy require fuel. (Miniseries)
The Gemini also appears in the Original Series as the ship where Cassiopeia is rescued in "Saga of a Star World".