Born in Steinbach, Manitoba, Canada, Hossack attended schools in Steinbach and Killarney, Manitoba, later graduating from the Brandon University School of Music in 1988 with a B.Mus. where she majored in voice. Shortly after graduation she was offered a lead part in a Toronto production of Frankenstein, but turned it down in order to appear on the TV series Another World.
Her television roles include Another World from 1989 to 1992; Cobra from 1993 to 1994; Profit in 1996; Hope Island in 1999; and Stephen King's Kingdom Hospital in 2004. She starred in the Canadian TV series, Falcon Beach in 2006. Hossack has made guest appearances on television shows such as Sliders, Mysterious Ways, Da Vinci's Inquest, The Outer Limits, Eureka,Stargate SG-1, Stargate: Atlantis, and Fringe. She played Mrs. Oliver on the TV series Reaper. She also played Deanna Campbell, the mother of Mary Winchester and the maternal grandmother of Dean Winchester and Sam Winchester on the CW paranormal/horror series Supernatural. Also a singer, Hossack resides in Toronto.
