Mark Robert Bailey (born 13 January 1965), known professionally as Bill Bailey, is an English musician, comedian, actor and television presenter. He is known for his role as Manny in the sitcom Black Books and for his regular appearances on the panel shows Never Mind the Buzzcocks, Have I Got News for You, and QI, as well as for his stand-up comedy work. He plays a variety of musical instruments and incorporates music into his performances.

Bailey was listed by The Observer as one of the 50 funniest acts in British comedy in 2003. In 2007, and again in 2010, he was voted the seventh greatest stand-up comic on Channel 4's 100 Greatest Stand-Ups. In 2020 Bailey won the 18th series of the televised BBC dancing competition Strictly Come Dancing with his professional partner Oti Mabuse. At 55, he is currently the oldest winner in the show's history as of 2024.