An interim championship is a temporary world championship that is awarded in three of the four major sanctioning bodies of professional boxing (WBA, WBC, and WBO) and in other combat sports, such as kickboxing and mixed martial arts.The IBF have no Interim Champions.

Occasionally, the world champion of a particular weight division is temporarily unable to defend his championship because of medical, legal, or other reasons that are beyond the champion's control. When this case occurs, two highly ranked contenders will fight for the interim championship of the same weight division—leading to two champions existing in the same weight division simultaneously. Once the world champion is able to return, he must fight against the interim champion. The winner of this bout reunifies the weight division as sole world champion. If the world champion cannot return or moves to a different weight division, the interim champion becomes the world champion.

Sanctioning bodies, however, often abuse the interim championship system. One example was in the WBC's flyweight division in 2005–2006. Pongsaklek Wonjongkam had defended his world title 11 consecutive times. Number-one contender Jorge Arce won an interim championship bout instead of receiving a title shot against Wonjongkam, who continued to defend his world title. Arce defended his interim championship four times before he vacated it in order to move up to super flyweight. Wonjongkam eventually set the flyweight division record for consecutive title defenses, without ever fighting against interim champion Arce.

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.

Dominick Rojelio Cruz (born September 3, 1985) is an Mexican American mixed martial artist who competes as a bantamweight in the Ultimate Fighting Championship and is the current UFC Bantamweight Champion. As of November 2011, Cruz is ranked the #1 bantamweight and #8 pound-for-pound fighter in the world by Sherdog.

Cruz began his professional MMA career fighting in the Rage in a Cage and Total Combat organizations.

His first fight in the WEC was at featherweight in a title fight against Urijah Faber in which he lost by guillotine choke in the first round. He would then make his debut for WEC's 135 lb Bantamweight division at WEC 34 defeating Charlie Valencia by unanimous decision and would go on to show domination of the 135 lb Bantamweight division beating the likes of Ian McCall, Ivan Lopez and handing top contender Joseph Benavidez his first loss at WEC 42 winning all bouts by unanimous decision and winning fight of the night honors in his bout versus Benavidez.

Cruz defeated Brian Bowles via TKO (doctor stoppage) on March, 6, 2010 at WEC 47. Bowles was unable to continue after the second round after breaking his hand. Cruz became the new WEC Bantamweight Champion.

Robert Glen "Robbie" Lawler (born March 20, 1982) is an American mixed martial artist Lawler was the EliteXC middleweight champion before EliteXC filed for bankruptcy. Lawler has recently signed with Strikeforce. He is a member of Team Hughes fighting out of H.I.T. Squad, a Granite City, Illinois gym, which he co-owns with teammate and former UFC welterweight champion Matt Hughes. MMAWeekly ranks Lawler as the #8 middleweight in the world.

On March 31, 2007, he fought Frank Trigg for the ICON Sport middleweight championship and won by KO in the fourth round. On September 15, 2007, he fought PRIDE Fighting Championships veteran Murilo "Ninja" Rua for the EliteXC middleweight championship and won by TKO in the third round.

Lawler was scheduled to fight Hawaii's Kala Hose for the ICON Sport Middleweight Championship on December 15, 2007 in Honolulu, Hawaii, he however pulled out of the fight due to an injury. Icon Sport stripped Lawler of the middleweight title on February 9, 2008 for failing to defend the title.

Nicholas Robert Diaz (born August 2, 1983) is a American mixed martial artist of Mexican descent. He is the former Strikeforce Welterweight Champion, WEC and IFC Welterweight Champion. He has competed in the Ultimate Fighting Championship, Pride Fighting Championships and Elite Xtreme Combat. Diaz was promoted to black belt in Brazilian Jiu-Jitsu by Cesar Gracie on May 8, 2007. Diaz trains at the Diaz brother's Cesar Gracie Jiu-Jitsu Academy in Lodi, California. Diaz holds the distinction of having never been submitted, and has been finished by strikes only once in 35 fights. He is currently ranked the #4 welterweight in the world by Sherdog, ESPN, MMAWeekly, and USA Today.

Diaz was born in Stockton , California. He is the older brother of UFC fighter Nate Diaz. He went to Tokay High School in Lodi for one year before dropping out. While a freshman, he was a member of the swimming team. Diaz has stated in the past that he is thankful his mother got him into swimming classes because swimming is one of the main reasons why his cardio is so impressive during his fights. Diaz has also said on multiple occasions that he had a hard childhood and grew up without his biological father.