Pierre Collingwood Donat (January 20, 1928 – September 10, 2018), known as Peter Donat, was a Canadian actor. He was a co-founding company member of the American Conservatory Theater, and a frequent player at the Stratford Festival. He was also known to television audiences for his roles as Elmo Tyson on the primetime soap opera Flamingo Road (1981-82) and as William Mulder, the father of Fox Mulder, on The X-Files (1995-99). He won a Theatre World Award for The First Gentleman (1957), and was nominated for a Genie Award for Best Supporting Actor for The Bay Boy (1984).

Pierre Collingwood Donat was born in Kentville, Nova Scotia, to a Canadian mother Marie (née Bardet) and a British father Philip Ernst Donat, a landscape gardener by trade. His German paternal grandfather, Ernst Emil Donat, immigrated to England from Prussia. His younger brother Richard was also an actor. His uncle was Oscar winning British actor Robert Donat.

Donat graduated from Acadia University, then studied at the Yale School of Drama. There, he first came to attention as a stage actor in the lead of a production of Cyrano de Bergerac.

In 1961, he played a leading role in Donald Jack's stage play The Canvas Barricade, the first Canadian play performed at the Stratford Festival.

Donat performed in many Shakespearean roles at the Stratford Festival, including A Midsummer Night's Dream, Troilus and Cressida, Julius Caesar, and Falstaff. A chance meeting with Tyrone Guthrie led him to be cast in his first Broadway production, The First Gentleman, earned him a 1957 Theatre World Award.

Donat was a prominent member of the American Conservatory Theater (ACT) in San Francisco for a number of years. He was also active in local theater, most notably playing his first singing role as Professor Higgins in the 1988 Cabrillo Stage production of My Fair Lady.

In 1995, he played Prospero in The Tempest at the Atlantic Theatre Festival.

In 2003, he starred as Hirst in No Man's Land for Toronto’s Soulpepper Theatre.