Dr. Gaius Baltar is a fictional character in the TV series Battlestar Galactica played by James Callis, a reimagining of Lord Baltar from the 1978 Battlestar Galactica series. He is one of the show's primary characters.

Battlestar Galactica (BSG) is an American military science fiction television series, and part of the Battlestar Galactica franchise. The show was developed by Ronald D. Moore and executive produced by Moore and David Eick as a re-imagining of the 1978 Battlestar Galactica television series created by Glen A. Larson. The pilot for the series first aired as a three-hour miniseries in December 2003 on the Sci-Fi Channel, which was then followed by four regular seasons, ending its run on March 20, 2009. The cast includes Edward James Olmos, Mary McDonnell, Katee Sackhoff, Jamie Bamber, James Callis, Tricia Helfer, and Grace Park.