World Extreme Cagefighting (WEC) was an American mixed martial arts (MMA) promotion. It was purchased by Zuffa, LLC, the parent company of Ultimate Fighting Championship (UFC), in 2006. In its final incarnation, it was made up of 3 weight classes: 135, 145 and 155 lbs. To accommodate the smaller fighters, the WEC's cage was 25 ft. in diameter—5 ft. smaller than the standard UFC cage.

The organization was started in 2001, by Scott Adams and Reed Harris. Between 2001 and 2006, most of their events were held at Tachi Palace Hotel & Casino in Lemoore, California, and aired on HDNet.

In December 2006, Zuffa purchased the WEC. With the purchase, the WEC continued as a separate promotion with its own roster of fighters. Adams was retained after the purchase as the organization's matchmaker. Harris and Adams were named co-General Managers and were both active in the new WEC. In 2008, Sean Shelby was named the new match-maker for the promotion by Zuffa.

Zuffa made several changes to the promotion after the purchase. It discontinued its pentagonal cage for a modified version of the UFC's octagonal cage. The championships of fighters who were contracted UFC fighters were vacated. The promotion moved to focus on lighter weight classes, abandoning their heavyweight and super heavyweight divisions and championships, and retaining their bantamweight and featherweight divisions—two divisions not then present in the UFC. After the purchase, several of the WEC events were held in Zuffa's hometown of Las Vegas, Nevada, much like the UFC.

Olaf Alfonso is a mixed martial artist and writer. Born to a Guatemalan mother and a Norwegian father (deceased) that was a famous television and motion picture animator/director. He is a former Palace Fighting Championship Welterweight Champion, a World Extreme Cagefighting veteran, a Contacto Extremo Champion, and has competed for PRIDE Fighting Championship. He has earned gold medals in various grappling events worldwide like Grapplers Quest.

Alfonso Wrestled and helped coach during part of his time while enlisted with the U.S. Airforce. He also competed in boxing and kickboxing during his time overseas. He was a former high school wrestling coach in Oregon. Alfonso is exceptionally known for getting brutally knocked out in some of his fights like Mach Sakurai who stopped Alfonso with a devastating overhand right punch in Pride.

Alfonso officially retired in 2010 due to injuries and to focus on his gym and working for MMA Mexico events as Color commentator.

Urijah Christopher Faber (born May 14, 1979) is an American mixed martial artist currently fighting as a bantamweight in the Ultimate Fighting Championship organization. Faber won the WEC featherweight championship at WEC 19 on March 17, 2006 and held the title for over two years until his loss to Mike Brown at WEC 36 on November 5, 2008. As of November 2011, Faber is ranked the #2 bantamweight in the world by Sherdog.

Faber is a Brazilian Jiu-Jitsu brown belt under Fabio "Pateta" Prado, who, under Carlson Gracie Jr., is a 5th degree black belt.

Faber was born on May 14, 1979, in Isla Vista, California, to Theo and Suzanne Faber, and grew up in Lincoln. He is of Dutch descent on his fathers side and Italian descent on his mothers side.^{[citation needed]} He went to Glen Edwards Middle School for Jr. High and Lincoln High School for high school. He has two siblings, an older brother named Ryan and a younger sister named Michaella. His sister almost died after a Thanksgiving 2011 car accident. Faber graduated from the University of California at Davis with a Bachelors degree in human development.

Anthony Pettis (born January 27, 1987) is an American mixed martial artist who competes in the lightweight division and is currently signed with the Ultimate Fighting Championship. A professional MMA competitor since 2007, Pettis has made a name for himself mainly fighting in his home state of Wisconsin. He is a former fighter for the World Extreme Cagefighting (WEC), where he was the last WEC Lightweight Champion before merging the promotion into the UFC.

Born to Eugene Pettis Jr. and Annette Garcia, Anthony Pettis grew up in the south side of Milwaukee, Wisconsin along with his older brother Ray Pettis and younger brother Sergio "Lil' Showtime" Pettis. Pettis is of Mexican and Puerto Rican ancestry, his grandfather Anglicized the family name from Perez to Pettis, to avoid discrimination. Pettis attended Dominican High School.

Anthony "Showtime" Pettis made his professional MMA debut in December 2007. He compiled an undefeated record of 8-0 in shows all based in Milwaukee, Wisconsin before debuting with the WEC. Pettis also has a professional kickboxing background.

Josh Richard Grispi (born October 14, 1988) is an American mixed martial artist who competes in the UFC featherweight division.

Grispi started mixed martial arts training when he was 13. It was suggested to him by his dad as an outlet when he got kicked out of a paintball facility after repeated scuffles with other players. He went to South Shore Sportfighting, where he still trains today. The sport grew on Grispi, and he began fighting and wrestling in New Hampshire and Massachusetts, winning local tournaments while often being the youngest competitor.

After beginning his career in 2006 and going 10-1 in smaller MMA promotions, Grispi was signed by World Extreme Cagefighting.

He made his WEC debut against Mark Hominick at WEC 32, locking in a rear naked choke in the first round. This was followed up by an early first round TKO victory over Micah Miller

His most notable victory at that point came against former UFC Lightweight champ Jens Pulver at WEC 41 on June 7, 2009. Two days before his Pulver fight, Grispi injured his ankle while training, but agreed to fight anyway. He underwent surgery and returned in the summer of 2010.