Daphne Kate Reid was born in London, England, the daughter of Canadian parents, Helen Isabel (née Moore) and Walter Clarke Reid, who was a former Bengal Lancer in the Indian army and a retired colonel. Reid attended Havergal College for high school and attended college in London, and then studied acting at a performance art school in Canada.

She had a long and varied career on film, television and stage in both Canada and the United States. Her stage roles included Lady Macbeth inMacbeth, Katharina in The Taming of the Shrew, Henny in Bosoms and Neglect, and Martha in Who's Afraid of Virginia Woolf.

Her film credits include The Andromeda Strain, A Delicate Balance, Sweet Hearts Dance, Atlantic City and The Best Damn Fiddler from Calabogie to Kaladar, and "Death of a Salesman". She played the scheming/domineering mother of Natalie Wood in This Property is Condemned, although she was only eight years older than the actress.

She played "Aunt Lil" on Dallas in the early 1980s, as well as appearing in episodes of Scarecrow and Mrs. King and Columbo.

• Officer of the Order of Canada (1974)
• ACTRA and Dora Mavor Moore awards (1980 and 1981, respectively)
• Earle Grey Award (1988)
• Honorary degrees from York University (1970) and the University of Toronto (1989)