Christopher O'Dowd (born 9 October 1979) is an Irish actor and comedian. He received wide attention as Roy Brenneman, one of the lead characters in the Channel 4 comedy The IT Crowd, which ran for four series from 2006 to 2010. He has starred in films including Gulliver's Travels (2010), Bridesmaids, Friends with Kids (2011), Cuban Fury (2014), Miss Peregrine's Home for Peculiar Children (2016) and The Cloverfield Paradox (2018). He created and starred in the Sky 1 television series Moone Boy, which aired from 2012 to 2015 and brought him Irish Film and Television Award nominations for acting, writing and directing.

Since 2017, he has appeared as Miles Daly in the Epix comedy series Get Shorty. He had a recurring role in the comedy-drama series Girls. His performance in the British comedy TV series State of the Union won him a Primetime Emmy Award. He made his Broadway debut in the play adaptation of Of Mice and Men in 2014, for which he was nominated for a Tony Award. In 2020, he was listed as #39 on The Irish Times list of Ireland's greatest film actors.