Guylaine St. Onge (June 1, 1965 – March 3, 2005) was a Canadian actress, model, and dancer. She was born in Saint-Eustache, Quebec, and raised in Saint-Hyacinthe. She began studying ballet at the age of four and later performed with a dance troupe in Montreal before moving into modeling and acting.

St. Onge began her screen career with a role in the Canadian television series Mount Royal in 1988. She went on to appear in several television productions, including a recurring role in Lonesome Dove: The Outlaw Years (1995–1996) and a leading role in the Showtime drama Fast Track (1997–1998). She also made guest appearances in series such as The Outer Limits, La Femme Nikita, and Mutant X.

In 2001, she appeared in the film Angel Eyes. One of her later roles was the character Juda in the fifth season of the science-fiction series Earth: Final Conflict.

Guylaine St. Onge died of cervical cancer on March 3, 2005, in Toronto, Ontario, at the age of 39.