Justin Mateen (born March 31, 1986) is a Jewish American internet entrepreneur of Iranian origin who is the co-founder and former CMO of popular dating app Tinder. He is also an early stage tech investor and company advisor. Some of his seed and early stage investments include companies like Lendup, Home Chef, StyleSeat, Munchery, and Hyperloop One. In 2014, Forbes listed Mateen in Forbes 30 under 30 and Fast Company listed him as one of the most creative people in business.

On June 30th 2014, Mateen's former girlfriend and Tinder VP of marketing Whitney Wolfe filed a sexual harassment and sexual discrimination suit in Los Angeles County Superior Court against IAC controlled Match Group, parent company of Tinder. The lawsuit alleged that her superiors, Sean Rad and Justin Mateen, had engaged in discrimination and sexual harassment while Tinder's corporate supervisors did nothing. After extensive investigation, IAC stated that although inappropriate messages had been exchanged, contradictory evidence was discovered and that Mateen, Rad and the company were innocent of any wrongdoing. IAC reached an agreement before trial and all claims were dismissed.

Mateen is a graduate of USC Marshall School of Business and is a member of alpha epsilon Pi. He is originally from Beverly Hills, CA.