James Callis is a British actor and writer. he is best known for playing Tom, Bridget's best friend in Bridget Jones's Diary (2001), Bridget Jones: Edge of Reason (2004) and Bridget Jones's Baby (2016). He played the character of Dr. Gaius Baltar on the Battlestar Galactica mini - series and later reprised his role in the Battlestar Galactica re-imagined series. Callis was also seen in Austenland (2013) and House by the Lake (2015).