Andrea Joy “A.J.” Cook was born on 22 July 1978, in Oshawa, Ontario, and spent most of her life growing up in Whitby. She has three siblings: Nathan, Paul, and Angela. In the second grade, she was declared legally blind because of severe astigmatism and wore contacts and thick glasses to correct her vision. In 2007, she underwent surgery, and a lens implant corrected the vision impairment.
Cook began dancing at the age of four and took jazz, tap, and ballet lessons. She competed competitively for many years, and at the age of 16, she decided that she wanted to try her hand at acting. She also taught dance in her younger years and has commented that if she had not become an actress, she would have most likely started a small dance studio. Cook also attended Anderson Collegiate Vocational Institute in Whitby.
Her first acting job was in a McDonald’s commercial in 1997. She eventually graduated to series work with a guest role on the television series Goosebumps, and parts in two television movies, In His Father’s Shoes and Elvis Meets Nixon. She is perhaps best known for her role as Supervisory Special Agent Jennifer “JJ” Jareau in the CBS crime drama Criminal Minds. Cook has also appeared in The Virgin Suicides (1999), Out Cold (2001), and Final Destination 2 (2003). In the 1999 feature film The Virgin Suicides, she played the role of one of five captivating suicidal sisters. Also in that year, she landed a starring role in the TV series Higher Ground, in which she played Shelby Merrick, a rough-around-the-edges teenage girl dealing with abuse and heartache at a wilderness school for struggling kids. The show lasted for one season, ending with a romance between Shelby and Hayden Christensen’s character, Scott. After Higher Ground, she appeared in the 2000 TV movie The Spiral Staircase (alongside Higher Ground alum Kandyse McClure). In 2003, Cook guest starred in Dead Like Me. She was also in season one of Tru Calling as Lindsay Walker.
A.J. Cook is a member of The Church of Jesus Christ of Latter-day Saints. On 3 August 2001, she married her long-time boyfriend, Nathan Andersen, who she met in a film class at Utah Valley University (UVU). She and her husband currently reside in Los Angeles, California, with their two sons. Their son, Mekhai, born in September 2008, made a brief appearance as Henry LaMontagne in Criminal Minds when Cook’s character is buying children’s medicine from a pharmacy. He reprised the role in the two-hour season seven finale in 2012 and several other episodes throughout the series. Their second son, Phoenix Sky, was born in July 2015.