Katie was born in Los Angeles, California on November 25th 2986 to parents David Cassidy, pop icon from the 1970's, and Sherry Benedon, a former model. She grew up in Calabasas, California with her mom and stepfather, Richard Benedon. Aside from her father, Katie has other famous relatives; her grandparents Jack Cassidy, Evelyn Ward and Shirley Jones, and her uncles Shaun and Ryan Cassidy. She has two older sisters, Jaime and Jenna, and a younger brother Beau.

From an early age, Katie has been interested in show business, taking lessons in singing, dancing, acting, gymnastics, guitar and piano as a child. She also cheered for the California Flyers and as a freshman at her high school, Calabasas High School. Although she wasn't allowed to pursue a professional career in acting until she completed high school, Katie attended a community theatre and studied with an acting coach before her graduation in 2005, as well as modeling for Abercrombie and Fitch's Rock and Republic clothing line in 2004.

In 2002, Katie released a song called "I Think I Love You" with Artemis Records, a cover of her father's song. While working with Artemis Records she met Greg Raposo of the band Dream Street who she dated in 2002. He wrote the song "We're in Love" for her. There she also met Jesse McCartney, the two were together for a few years. She appeared in his music video for the song "She's No You".

After high school, Katie moved to Los Angeles to pursue acting. She landed a role as Zoe in the popular TV show "7th Heaven" appearing in four episodes, as well as two episodes of "Sex, Love & Secrets". Then came a string of films, "When a Stranger Calls", "The Lost", "Click" and "Black Christmas", all released in 2006. In 2007 she did three more movies, "You Are Here", "Live!" and "Walk the Talk" as well as "Taken" in 2008.

Katie because popular when she appeared as the mysterious demon Ruby on the CW series "Supernatural" alongside Jared Padalecki and Jensen Ackles. She did six episodes for season three which aired in 2007 and 2008. Fans of the show were unsure at first about Ruby as the show had always been centered around Sam and Dean, but warmed to her. At the end of the sesaon, Warner Brothers were unsure of what they were going to do with the character of Ruby (rumored to be due to budget costs) and Katie had the option to stay or leave. When "Harper's Island" came about it was something she really wanted to do, so she left "Supernatural". She enjoyed working on both projects.

Katie is currently working on "Melrose Place" as Ella Simms, a character she is having lots of fun with. Also coming up for Katie are the films "Fencewalker" and "A Nightmare on Elm Street", and she may appear alongside John Travolta in "Dallas", a movie adaptation of the TV series.

When Katie isn't working she enjoys reading, yoga, watching movies and studying different aspects of film. She would like to produce or direct at some point, and has recently been studying comedy. Katie is truly passionate about the industry and we'll be seeing her around for years to come!