Stephen J. Dillane (born 30 November 1956) is an English actor. He won a Tony Award for his lead performance in Tom Stoppard's play The Real Thing.

Dillane was born in Kensington, London, to an English mother, Bridget (Curwen), and an Australian surgeon father, John Dillane. He read history and political science at the University of Exeter and afterward became a journalist for the Croydon Advertiser. Unhappy in his career, he read how actor Trevor Eve gave up architecture for acting and was thus inspired to enter the Bristol Old Vic Theatre School.

Dillane is a distinguished theatre actor and his notable roles include Archer in The Beaux' Stratagem (Royal National Theatre, 1989; spelled Stephen Dillon on the poster), Prior Walter in Angels in America (1993), Hamlet (1994), Clov in Samuel Beckett's Endgame (1996), Uncle Vanya (1998), Henry in Tom Stoppard's The Real Thing (for which he won a Tony Award in 2000) and a one-man version of Macbeth (2005). He has also performed T.S. Eliot's 'Four Quartets' in London and New York City, and is soon to be seen in the 2010 Bridge Project's productions of 'The Tempest' and 'As You Like It'.