- Due to Alopecia, lost all his hair at age 6.
- Attended the same boarding school as Sacha Baron Cohen, who was in Lucas's older brother's class.
- Met longtime comedy collaborator David Walliams when both attended the National Youth Theater (which also boasts alumni such as Helen Mirren and Daniel Craig). The pair debuted on stage together in 1995 at the Edinburgh Fringe Festival.
- Lucas and Walliams co-created Little Britain for BBC 4 Radio in 2001, BBC television in 2003 and then HBO (as Little Britain USA) in 2008.
- Entered into a civil partnership with Kevin McGee at a December 2006 ceremony, which included guests such as Elton John and Courtney Love; the union was legally dissolved in October 2008.