Question: On which television show does Katie Cassidy play the fictional character, Ruby?

Related documents: [0]  [DOC] Katherine Evelyn Anita Cassidy (born November 25, 1986) is an American actress. After initially appearing in minor television roles, she made her film debut in "When a Stranger Calls" (2006). During the same year, she also had her first starring role as Kelli Presley in "Black Christmas" (2006). In 2007, Cassidy gained attention for her role as Ruby on the supernatural-horror television series "Supernatural", during its third season. She later had a supporting role in "Taken". In 2009, Cassidy became a cast member of the series "Harper's Island" and "Melrose Place", both of which lasted for only one season. During 2010, she had a supporting role as Kris Fowles in "A Nightmare on Elm Street" and a recurring role during the fourth season of "Gossip Girl". [END] 
[1]  [DOC] Ruby is a fictional character on The CW Television Network's "Supernatural" portrayed mainly by actresses Katie Cassidy and Genevieve Cortese. Created by the writers to expand on the characterization of demons within the series, she first appears in the third season, wherein she assists series protagonists Sam and Dean Winchester in fighting her fellow demons. By the fourth season, she has won Sam's trust and begins training him to kill demons with his psychic powers, though Dean remains fearful of ulterior motives. The character departs the series at the end of the fourth season. Though the fans at first reacted negatively towards Cortese replacing Cassidy after the third season, Cortese and creator Eric Kripke felt that they became more accepting as the fourth season progressed. While fan response to the character was mixed overall, critical reception was generally negative. A common criticism was underwhelming performances by Cassidy and Cortese. [END]  
Answer: Supernatural
Supernatural