Peter Thomas Donaldson (29 October 1953 – 8 January 2011) was a Canadian actor. He met actress Sheila McCarthy in 1983 while working in theatre in London, Ontario, and they were married in December 1986 in Stratford. The couple had two daughters. Peter died quietly at Princess Margaret Hospital, his wife and daughters at his side.

Donaldson was known for his stage work in Shakespearean roles, particularly at the Stratford Festival in Stratford, Ontario.He auditioned for the festival without success in 1975, but was hired years later by artistic director Robin Phillips, making his debut in Romeo and Juliet in 1977. He subsequently spent 24 seasons at the festival. Highlights of his career included his 2004 performance in Timon of Athens, as well as roles in To Kill a Mockingbird, The Seagull, Who's Afraid of Virginia Woolf. His performance of Jamie in Long Day's Journey Into Night at Stratford in 1995 was widely praised. Toronto critic Richard Ouzounian later noted that "Of all the fine actors I've ever seen in the part, only Donaldson gave us the charm as well as the pathos, the hope as well as the despair". He received a Genie award for this performance when it was filmed by David Wellington in 1996 for the film adaptation Long Day's Journey into Night. He also worked at the Shaw Festival, and in London as part of Robin Phillips' repertory company at the Grand Theatre.

Donaldson appeared in two CBC television series based on L.M. Montgomery books. He played Ian Bowles in Emily of New Moon and Reverend Leonard in Road to Avonlea. He also appeared in the TV series Little Mosque on the Prairie and Hangman, the eleventh episode of the third season of the Murdoch Mysteries and the thirty-seventh episode of the series.

His film work also included the Atom Egoyan film, The Sweet Hereafter. He also played John Adams in the six-part 1997 PBS television documentary Liberty! The American Revolution.

Community content is available under CC-BY-SA unless otherwise noted.