Barnaby Kay (born 9 April 1969) is a British actor, noted for his roles in television, stage and film, and as a member of the Royal Shakespeare Company. Kay is the son of the actor Richard Kay (1937 - 1985), and the grandson of entertainer Arthur Kay (died 1970). He is married to fellow actress Nicola Walker, with whom he has a son, Harry.

Among other roles, Kay has appeared in Wuthering Heights (2009), Holby City (2008), Midsomer Murders (2005), Spooks (2004), Silent Witness (2002), Conspiracy (2001), Casualty (1999), Shakespeare in Love (1998), Croupier (1998),Jonathan Creek (1997) and Minder (1994). His theatre work includes A Streetcar Named Desire at the Donmar Warehouse (2009), Orlando in As You Like It at the Novello Theatre (2006), Closer at the National Theatre (1999 - 2000), Pierre Bezuhov in War And Peace at the Hampstead Theatre (2008), Steve Calhanm in Eric Larue at the Soho Theatre (2006), and Alexander Petrovich Kalabushkin in Dying For It at the Almeida Theatre (2007).