Jennifer Jareau, often referred to as JJ, is a fictional character from the television series Criminal Minds. She serves as a communications liaison for the BAU (Behavioral Analysis Unit) and is known for her strong interpersonal skills and ability to connect with victims' families. JJ is portrayed by actress A.J. Cook. Throughout the series, JJ evolves from a support role to a more active position within the team, showcasing her investigative talents. She is characterized by her dedication to her work and her compassion for others, making her a vital member of the BAU team.