Andrea Joy “A. J.” Cook (born July 22, 1978) is a Canadian actress known for her role as Supervisory Special Agent Jennifer “JJ” Jareau in the CBS crime drama Criminal Minds. She has also appeared in films such as The Virgin Suicides (1999), Out Cold (2001), and Final Destination 2 (2003).

Cook was born in Oshawa, Ontario, and spent most of her life growing up in nearby Whitby, where she attended Anderson Collegiate Vocational Institute. She has three siblings: Nathan, Paul, and Angela. Cook was declared legally blind in the second grade because of a severe astigmatism, but wore contacts and thick glasses to correct her vision. In 2007 she underwent surgery during which a lens implant corrected the impairment. A dancer from age four, Cook began taking jazz, tap and ballet lessons. She danced competitively for many years, before deciding at the age of 16 that she wanted to try acting. Cook also taught dance when she was younger and has stated that if she hadn’t become an actress, she would most likely have set up a small dance studio somewhere. In an interview, she admitted that she still tap dances.