'Supernatural' angel heads to 'Nikita': Julie McNiven's sleeper assassin wakes up

"Supernatural" and "Nikita" will be sharing a night for the first time this fall when they premiere on The CW on Sept. 23 -- and now, a "Supernatural" alum will be stepping into the assassin vs. assassin world of "Nikita."

Julie McNiven, who played the traitorous angel Anna on "Supernatural" in the fourth and fifth seasons, is joining "Nikita" as a guest star in episode 2, airing Sept. 30. Zap2it confirms exclusively that McNiven plays Alicia, described as "a young woman with a troubled past who is completely unaware that she is a sleeper assassin."

When Nikita (Maggie Q) stops Alicia from committing a violent crime, she learns who is responsible for her abilities heightened killer instincts. She becomes a valuable resource for the team, and we'll learn that she has a lot in common with Birkhoff (Aaron Sanford).

McNiven is also known for her work as Hildy on "Mad Men" and as Ginn on "SGU: Stargate Universe."