Omar Mir Seddique Mateen was an American terrorist and mass murderer who murdered 49 people and wounded 53 others in a mass shooting at the Pulse nightclub in Orlando, Florida, on June 12, 2016, before he was killed in a shootout with the local police. It was the deadliest shooting by a single shooter in United States history until the Las Vegas Strip shooting on October 1, 2017.

Pulse was a gay bar, dance club, and nightclub in Orlando, Florida, founded in 2004 by Barbara Poma and Ron Legler. On June 12, 2016, the club was the scene of the second worst mass shooting by a single gunman in U.S. history, and the second deadliest terrorist attack on U.S. soil since the September 11 attacks. Forty-nine people were killed and 53 other people were injured.