Daughter of David Cassidy.

Did a cover of her father's song, "I Think I Love You".

Granddaughter of the late Jack Cassidy.

Has appeared in two remakes of two classical movie thrillers: When a Stranger Calls (2006) (originally released in 1979) and Black Christmas (2006) (originally released in 1974).

Has 2 older sisters, Jenna & Jaime.

Jesse McCartney wrote his song "Tell Her" for Katie.

Was going to appear in a 2007 remake of Revenge of the Nerds (1984) starring Adam Brody but after three weeks of filming the project was canceled.

According to her, the best part about acting is that she loves doing it and the worst part is the fact that it involves long hours and attracts too much media attention.

Katie attended the Round Meadow Elementary School and A.E. Wright Middle School.

Katie was named after Katherine Hepburn.

Jesse McCartney took Katie to Hawaii (her favorite vacation spot) to celebrate their first anniversary together.

Katie's good friend Greg Raposo wrote a song for her called "We're in Love".

As of 2008, Katie resides in Los Angeles.

Katie is a skilled guitarist and a pianist.

In 2004, Katie modeled for brands like Abercrombie & Fitch and Guess.

For her role on Supernatural, Katie had to get herself some kickboxing training.

In her spare time, Katie takes yoga and dance lessons.

Katie's role on the TV show Supernatural was cut from being a regular to a guest star due to budgetary concerns of the show.

For her part as a demon hunter in Supernatural, she watched some Discovery Channel to study how predatory animals go after their prey. She also watched action movies like Basic Instinct to prepare for the role.

Katie did a cover of her father's song "I Think I Love You".

Katie's other film credits include The Lost (2005), Walk the Talk (2007), and Live! (2007).

Katie received a Calabasas High School senior award for community service.

As a young girl, Katie kept singing along with the radio.

Katie appeared in Jesse McCartney's music video for his song "She's No You" in 2005.

Katie traveled along on her boyfriend's US tour in 2005. That same year, she, her family, and her boyfriend, Jesse McCartney, took a trip to Costa Rica in 2005.

Katie is good friends with Lindsay Pagano and Supernatural co-star Jared Padalecki.

Katie started doing theater when she was in elementary school.

Katie was named one of the most beautiful people of 2006 in PAPER magazine.

Katie received a brand new truck from her parents for her 16th birthday.