Canadian-American stage and screen actor Peter Donat passed away September 10 at age 90. His wife, Maria, told The New York Times that the cause was complications of diabetes.

Donat made his Broadway debut in the 1957 production of The First Gentleman, followed by roles in The Country Wife (1957); The Entertainer (1958); The Chinese Prime Minister (1958); and There's One in Every Marriage (1972).

Though known to many for his recurring onscreen role as William Mulder, Agent Mulder’s father in The X-Files, Donat performed frequently onstage in regional productions. He was an original company member at San Francisco's American Conservatory Theater where he performed in Cyrano de Bergerac, Under Milkwood, Tartuffe, Staircase, Little Murders, The Architect and the Emperor of Assyria, The Importance of Being Earnest, and in the title role of Hadrian VII, among others.

He also performed in numerous seasons at the Stratford Festival in Canada in the roles of Cassius in Julius Caesar and Troilus in Troilus and Cressida, among others.

Other film and television credits included recurring roles on Time Trax and Flamingo Road, as well as appearances on Murder, She Wrote, Hawaii Five-O, and The F.B.I., among other TV shows. He appeared in the films The Game, The Godfather: Part II, and The War of the Roses.