Katherine Evelyn Anita "Katie" Cassidy (born November 25, 1986) is an American actress who stars as Laurel Lance on The CW superhero television seriesArrow (2012–present). She has also appeared in The CW series Supernatural (2007–2008), Melrose Place (2009–2010), and Gossip Girl (2010 and 2012); in CBS'Harper's Island (2009); and in the films When a Stranger Calls (2006), Black Christmas (2006), Taken (2008), A Nightmare on Elm Street (2010) and Monte Carlo(2011). Cassidy has roles in the upcoming films Fencewalker and The Scribbler.

Cassidy was born in Los Angeles, the daughter of actor David Cassidy and model Sherry Williams, who first met and dated in early 1970, then had an off and on relationship over the next sixteen years. Cassidy's paternal grandparents were actors Jack Cassidy and Evelyn Ward, and she is the niece of teen idol and television producer Shaun Cassidy and actor Patrick Cassidy.

Cassidy grew up in Calabasas, California with her mother and stepfather, Richard Benedon, an ER physician. She has two older half-sisters, Jenna and Jamie, and a younger half-brother, Beau Cassidy.

As a child, Cassidy took to tumbling, competing and eventually became a cheerleader for the California Flyers, a competitive team. She cheered as a freshman forCalabasas High School where she attended high school and graduated with honors in 2005.

While in elementary school, Cassidy became interested in show business and participated in several community theatre productions beginning at the age of 7, and as a teenager studied with an acting coach. She did some modeling which culminated in a campaign ad for Abercrombie and Fitch in 2004. Her mother would not allow her to act professionally until completing her high school education with college prep courses.

Cassidy is a spokesperson for the charity H.E.L.P. Malawi.

Cassidy was in a relationship with Jesse McCartney for four years. She also dated Jarret Stoll, a Canadian ice hockey player, for two years until December 2011. In 2012, she briefly dated actorJerry Ferrara. She has been dating Jason Garrison, a Canadian ice hockey defenceman, since June 2013.