Melvin Paul Guillard, Jr. (born March 30, 1983) is an American mixed martial artist currently fighting in the lightweight division for the Ultimate Fighting Championship (UFC). He debuted with the company onThe Ultimate Fighter 2 television series, losing in the first welterweight elimination bout to Josh Burkman. Guillard received his blue belt in Brazilian Jiu-Jitsu under Ricco Rodriguez in 2008.

In 2005 Guillard fought against Roger Huerta. After Guillard took a competitive decision victory, the fight was ruled a no contest after Huerta appealed the commission making an accusation that Guillard was greasing between rounds.

Guillard later participated in The Ultimate Fighter 2, but was eliminated from the competition after losing by unanimous decision against Josh Burkman. Guillard returned at the season finale, defeating Marcus Davis by technical knockout. Fighting again at welterweight, Guillard lost his next fight, against Josh Neer, by triangle choke submission which surprised many in attendance. Guillard seemed to control the fight until then, opening a large cut on Neer's forehead in the process.

When the lightweight division was reinstated at UFC 58, Guillard began to transition to the lighter weight class. He made his lightweight debut in the UFC at UFC 60, defeating Rick Davis by first round knockout. On September 23, 2006 Guillard fought former WEC lightweight champion Gabe Ruediger, at UFC 63. Guillard won the fight via KO with a body blow. Guillard lost his fight against Rich Clementi at UFC 79 by rear-naked choke at 4:40 of the first round. Both before and after the bout there was heated trash talking which included Guillard giving Clementi the finger during the introductions. Guillard also attempted to attack Clementi after being submitted, but was restrained by referee Herb Dean.

Guillard was slated to fight Spencer Fisher at UFC 90 in Chicago on October 25, 2008, but was replaced by Shannon Gugerty due to a torn ACL. Guillard defeated Gleison Tibau at TUF 9 Finale by split decision June 20, 2009 in a highly controversial fight where many had Tibau as the winner. Tibau scored numerous takedowns, but was unable to inflict much damage on the ground. For reasons unexplained, the judges scorecards were not read, only the result. Guillard was defeated via guillotine choke by Nate Diaz on September 16, 2009 at UFC Fight Night 19.

Guillard next faced Ronnys Torres on February 6, 2010 at UFC 109. Melvin recently joined well respected coach Greg Jackson's camp out in Albuquerque, New Mexico. Guillard showing improved submission defense and patience in the fight, won via unanimous decision (29-28, 29-28, 29-28).

Guillard was scheduled to face Thiago Tavares on May 29, 2010 at UFC 114, but Tavares was forced off the card with an elbow injury. Guillard fought and defeated UFC newcomer Waylon Lowe by the way of KO in the first round.

Guillard defeated Jeremy Stephens on September 25, 2010 at UFC 119.

Guillard was expected to face Yves Edwards on January 22, 2011 at UFC Fight Night 23. However, on December 6, 2010, headliner Kenny Florian pulled out of a fight with Evan Dunham due to injury and Guillard has been chosen as his replacement. Guillard would go on to defeat Dunham in the first round via TKO due to knees. The finish earned him Knockout of the Night honors.

Guillard is expected to face Shane Roller on July 2, 2011 at UFC 132.