George Sullivan (born March 13, 1981) is an American retired mixed martial artist who competed in the Welterweight and Middleweight divisions. A professional mixed martial artist from 2006 till 2023, Sullivan had most notably competed in the Ultimate Fighting Championship.

Sullivan made his professional debut in 2006 competing in regional promotions in his native New Jersey, compiled a record of 14–3, and won the Cage Fury Fighting Championships Welterweight Championship. Sullivan signed with the UFC in the winter of 2013.

Sullivan made his promotional debut against fellow newcomer Mike Rhodes on January 25, 2014, at UFC on Fox 10. Sullivan won the fight via unanimous decision.

In his next fight, Sullivan faced Igor Araújo on September 13, 2014, at UFC Fight Night 51. After winning the first round, Sullivan won the bout via knockout in the second round as he was able to land several punches from within Araújo's half guard, forcing the referee to stop the fight.

Sullivan was expected to face Kenny Robertson on April 18, 2015, at UFC on Fox 15. However, Robertson pulled out of the bout citing injury and was replaced by Tim Means. He lost the back and forth fight via submission in the third round.

Sullivan was expected to face Marcio Alexandre Jr. on July 12, 2015, at The Ultimate Fighter 21 Finale. However, Alexandre pulled out of the fight during the week leading up to the event citing a rib injury and was replaced by promotional newcomer Dominic Waters. Sullivan won the one-sided fight via unanimous decision.

Sullivan faced Alexander Yakovlev at UFC on Fox 18 on January 30, 2016. He lost the fight via knockout in the first round.

Sullivan was expected to face Héctor Urbina on July 23, 2016, at UFC on Fox 20. However, Sullivan was pulled from the event due to a "potential compliance issue" with the UFC's anti-doping policy stemming from "voluntarily disclosed information" he provided to USADA.