An actor who had plied his trade on the stage and screen for nearly a decade by the time he was cast as brilliant but traitorous Dr. Gaius Baltar on the hit sci-fi series Battlestar Galactica, James Callis displayed the pitch-perfect combination of swaggering arrogance and dangerous cowardice needed to betray the human race to its robotic oppressors. It was after studying English and literature at the University of York that the English-born actor enrolled in the prestigious London Academy of Music and Art, and after graduating in 1996, Callis quickly moved on the West End stage -- where he made his professional debut opposite Bob Hoskins in a production of Old Wicked Songs. Dubbed "Most Promising Newcomer" at the London Critic's Circle for his performance in that play, Callis subsequently appeared in an Almeida Theatre production of The Doctor's Dilemma and a Soho Theatre production of Things You Shouldn't Say Past Midnight. A brief appearance in the British television series Murder Most Horrid helped to kick-start Callis's television career, with roles in The Ruth Rendell Mysteries and Sex, Chips and Rock n' Roll following in quick succession. In 2001, Callis made his move into features with a supporting role in the hit comedy Bridget Jones's Diary (a role he would later reprise in the film's 2004 sequel, Bridget Jones: The Edge of Reason). Callis also made his feature directorial debut in 2001 when he collaborated with writer/director Nick Cohen on the independent comedy Beginner's Luck, in which he also acted. While Callis's feature roles no doubt helped to improve his profile, it was the actor's memorably devious performance as the scientist who sells out the human race on Battlestar Galactica that established him as a true international star.