This is something I did on another site and I’m going to put it here for MMA fans: It’s a somewhat comprehensive listing of the current major MMA World Champions using the most up-to-date info and records I can find (sometimes that’s easier said than done!). Champions are listed by weight class along with how many times they’ve held the belt before, if they have, the date they won the title, and in some cases where info permits the number of successful defenses and next scheduled defense. All weight classes are listed in pounds unless otherwise noted.

This list was last updated on 11/19/09.

Ultimate Fighting Championship (UFC)

Lightweight (146-155): B.J. Penn. 1st reign. Champion since: 1/19/08. Successful defenses: 2 with 1 loss in a non-title fight. Next defense: 12/12/09 vs. Diego Sanchez.

Welterweight (156-170): Georges St. Pierre. 3rd reign (includes 1 interim championship). Champion since: 4/19/08. Successful defenses: 3. Next defense: TBA in 2010 vs. Dan Hardy.

Middleweight (171-185): Anderson Silva. 1st reign. Champion since: 10/14/06. Successful defenses: 5 with 2 wins in non-title fights. Next defense: 2/6/10 vs. Vitor Belfort.

Light Heavyweight (186-205): Ryoto (Lyoto) Machida. 1st reign. Champion since: 5/23/09. Successful defenses: 1. Next defense: 5/1/10 vs. Mauricio Rua (again).

Heavyweight (206-265): Brock Lesnar. 1st reign. Champion since: 11/15/08. Successful defenses: 1. Next defense: TBA.
10/26/09 UPDATE: Lesnar’s scheduled 11/21/09 defense vs. Shane Carwin is now off due to a Lesnar illness. No word yet on when/if the fight will be rescheduled.
11/5/09 UPDATE: The fight now won’t happen until an unknown date in ‘10 due to Lesnar having mononucleosis, a worse illness than originally suspected.
11/16/09 UDPATE: Lesnar’s illness is serious to the point that, fighting-wise, he may be done.
11/18/09 UPDATE: Lesnar is out of the hospital and at home recovering for now. Still no possible return date set. The interim title will be brought back for now.

Interim Heavyweight: VACANT. Title to be re-created by UFC in late ‘09-early ‘10 due to Lesnar illness and uncertainty about his return.

World Extreme Cagefighting (WEC)

Flyweight (up to 125): VACANT. No champion yet. Division created on 2/3/09 and will be implemented at a later date.
8/7/09 UPDATE: Implementation now appears likely to be in early ‘10.

Bantamweight (126-135): Brian Bowles. 1st reign. Champion since: 8/9/09. Successful defenses: None. Next defense: TBA.
Note: While his first challenger has not been confirmed yet, it’s expected to be Dominick Cruz.

Featherweight (136-145): Jose Aldo. 1st reign. Champion since: 11/18/09. Successful defenses: None. Next defense: TBA.

Lightweight (146-155):  Jamie Varner. 1st reign. Champion since: 2/13/08. Successful defenses: 2. Next defense: 1/10/10 vs. Benson (Ben) Henderson (fight to unify LW titles and determine undisputed champion).

Interim Lightweight: Benson (Ben) Henderson. 1st reign. Champion since: 10/10/09 (inaugural champion). Successful defenses: None. Next defense: 1/10/10 vs. Jamie Varner (fight to unify titles and determine undisputed champion).

Welterweight (156-170): RETIRED. Title retired after WEC 39 in March 2009 when division integrated into UFC. Carlos Condit, who held the title since winning it on 3/24/07 (3 successful defenses), was the final champion.

Middleweight (171-185): RETIRED. Title retired after WEC 37 in December 2008 when division integrated into UFC. Title vacated after WEC 36 in November 2008 by Paulo Filho after losing a non-title fight against Chael Sonnen, fight changed from title to non-title when Filho missed weight.

Light Heavyweight (186-205): RETIRED. Title retired after WEC 37 in December 2008 when division integrated into UFC. Steve Cantwell, who held the title since winning it on 8/3/08, was the final champion.

Strikeforce

Lightweight (146-155): Josh Thomson. 1st reign. Champion since: 6/27/08. Successful defenses: None with 1 win in a non-title fight. Next defense: 12/19/09 vs. Gilbert Melendez (tentative).

Interim Lightweight: Gilbert Melendez. 2nd reign (includes 1 LW Title reign). Champion since: 4/11/09. Successful defenses: 1. Next defense: 12/19/09 vs. Josh Thomson (tentative-fight to unify LW Titles and determine undisputed champion).
Note: Whoever is the interim champion will get an immediate title unification fight against Thomson upon his return.

Welterweight (156-170): VACANT.

Middleweight (171-185): Jake Shields. 1st reign. Champion since: 11/7/09. Successful defenses: None. Next defense: TBA.
Note: Shields may defend against the winner of Matt Lindland vs. Ronaldo Souza on 12/19/09.

Light Heavyweight (186-205): Gegard Mousasi. 1st reign. Champion since: 8/15/09. Successful defenses: None with 1 win in a non-title fight. Next defense: TBA.

Heavyweight (206-265): Alistair Overeem. 1st reign. Champion since: 11/16/07. Successful defenses: None. Next defense: TBA.
9/5/09 UPDATE: Overeem won’t defend until ‘10 following K-1 and other commitments.
10/16/09 UPDATE: According to SF CEO Scott Coker, Overeem is expected to defend in February or March at the latest.

Women (145): Cristiane Santos. 1st reign. Champion since: 8/15/09 (inaugural champion). Successful defenses: None. Next defense: 1/30/10 (tentative) vs. Marloes Coenen.

Bellator Fighting Championships

Note: Bellator is a new made-for-TV promotion created in Spring ‘09 in partnership with ESPN. They ran weekly events featuring tournaments to determine division champions and non-tournament fights during their first season which ran 12 weeks. They will return for a second season of events later this year. It is expected that the inaugural champion in each weight class will first defend against the winner of another tournament to be held during the  promotion’s second season. While the inaugural champions will not defend their titles until near the end of season 2, their contracts allow them some flexibility to fight outside the promotion until then.
10/19/09 UPDATE: The second season will start in April ‘10, so expect title defenses in June or July. A 3rd season will start in August ‘10.

Featherweight (136-145): Joe Soto. 1st reign. Champion since: 6/5/09 (inaugural champion). Successful defenses: None.

Lightweight (146-155): Eddie Alvarez. 1st reign. Champion since: 6/19/09 (inaugural champion). Successful defenses: None.

Welterweight (156-170): Lyman Good. 1st reign. Champion since: 6/12/09 (inaugural champion). Successful defenses: None.

Middleweight (171-185): Hector Lombard. 1st reign. Champion since: 6/19/09 (inaugural champion). Successful defenses: None.

DREAM (Japan)

Featherweight (up to 139): Bibiano Fernandes. 1st reign. Champion since: 10/6/09 (inaugural champion). Successful defenses: None. Next defense: TBA.

Lightweight (140-154): Shinya Aoki. 1st reign. Champion since: 10/6/09. Successful defenses: None. Next defense: 12/31/09 vs. Tatsuya Kawajiri (tentative).

Welterweight (155-168): Marius Zaromskis. 1st reign. Champion since: 7/20/09 (inaugural champion). Successful defenses: None with 1 win in a non-title match. Next defense: TBA.

Middleweight (169-185): VACANT. Previous champion Gegard Mousasi vacated title on 4/14/09 due to moving to Light Heavyweight. Determination fight between Jason Miller and Ronaldo Souza on 5/26/09 to crown a new champion ended in a No Contest. Therefore the title remains vacant. Planned rematch for 10/6/09 was ultimately cancelled due to both signing with Strikeforce and Miller having a title fight on 11/7/09.

Light Heavyweight (186-205): VACANT. No champion yet.

Heavyweight (206+): VACANT. No champion yet.

World Victory Road (Sengoku) (Japan)

Featherweight: VACANT. No champion yet.
Note: The promotion’s Featherweight GP, which may determine a participant in an eventual determination match to crown the first champion, was won by Masanori Kanehara.
10/13/09 UPDATE: Determination match to crown inaugural champion scheduled for 12/31/09 at the latest.

Lightweight: Mizuto Hirota. 1st reign. Champion since: 8/2/09. Successful defenses: None. Next defense: 12/31/09 vs. TBA, possibly Kazunori Yokota.

Welterweight: VACANT. No champion yet.
10/13/09 UPDATE: Determination match to crown inaugural champion scheduled for 12/31/09 at the latest.

Middleweight: Jorge Santiago. 1st reign. Champion since: 1/4/09 (inaugural champion). Successful defenses: None with 1 loss in a non-title fight. Next defense: 12/31/09 vs. TBA.

Heavyweight: VACANT. No champion yet. Title reportedly to be created by Sengoku in late ‘09. Determination fight possible for December ‘09 to crown inaugural champion.

Pancrase Hybrid Wrestling (Pancrase) (Japan)

Note: The promotion refers to each division champion as “King Of Pancrase”.

Flyweight (up to 127.9): Mitsuhisa Sunabe. 1st reign. Champion since: 6/7/09 (inaugural champion). Successful defenses: 1.

Bantamweight (128-134.9): Manabu Inoue. 1st reign. Champion since: 12/7/08 (inaugural champion). Successful defenses: None with 1 win in a non-title fight.

Featherweight (135-144.9): Marlon Sandro. 1st reign. Champion since: 10/26/08. Successful defenses: None with 3 wins and 1 loss in non-title matches.
Note: Sandro is next expected to fight on 12/31/09 but it’s not known if it will be a title match. In all likelihood he’ll fight for a title, but not defend his.

Lightweight (145-154.9): Maximo Blanco. 1st reign. Champion since: 8/8/09. Successful defenses: None with 1 win in a non-title fight.

Welterweight (155-169.9): Takuya Wada. 1st reign. Champion since: 4/27/08. Successful defenses: 2.
Note: Wada will next face Shiko Yamashita on 11/23 in a NON-TITLE match in Shooto.

Middleweight (170-184.9): Izuru Takeuchi. 1st reign. Champion since: 11/28/07. Successful defenses: 3. Next defense: 12/6/09 vs. Ichiro Kanai.
Note: Most recent (3rd) title defense on 8/8/09 ended in a Draw. Takeuchi retained the title as a result.

Light Heavyweight (185-204.9): Ryo Kawamura. 1st reign. Champion since: 10/1/08. Successful defenses: None with 1 win and 2 losses in non-title fights. Next defense: 12/6/09 vs. Shunsuke Inoue.

Heavyweight (205-265): VACANT. Previous champion Assuerio Silva vacated title in January 2008 due to signing an exclusive contract with Hardcore Championship Fighting. Class weight limits were then changed from 196-221 to 206-265 when the promotion adopted the Unified MMA Rules weight classes.

Super Heavyweight (221+): RETIRED. Title retired in January 2008 due to Pancrase adopting the Unified MMA Rules weight classes and expanding Heavyweight class. Tsuyoshi Kosaka was the only champion, reigning from 11/7/04 until vacating title in ‘06.

Openweight (No limit): Josh Barnett. 1st reign. Champion since: 8/31/03. Successful defenses: 2.

DEEP (Japan)

Megaton (206+): Yusuke Kawaguchi. Champion since: 8/2/08 (inaugural champion). Successful defenses: 2.
Note: Kawaguchi will face Roque Martinez on 12/19/09 but it’s not yet known if it will be for the title.

Light Heavyweight: VACANT. No champion yet. Title to be created by DEEP in December 2009.

Middleweight: Riki Fukuda. Champion since: 6/30/09. Successful defenses: None.

Welterweight: Seichi Ikemoto. Champion since: 7/27/08. Successful defenses: 1 with 1 loss in a non-title match.

Lightweight:  Katsunori Kikuno. Champion since: 4/16/09. Successful defenses: None with 1 win and 1 loss in non-title matches.

Featherweight: Takafumi Otsuka. Champion since: 8/23/09. Successful defenses: None.

Bantamweight: Masakazu Imanari. Champion since: 8/17/08. Successful defenses: 1 with 1 win and 1 loss in non-title matches.
Note: Imanari will face Justin Cruz on 12/19/09, but it’s not yet known if it’s a title match.

Women’s Lightweight: Miku Matsumoto. Champion since: 8/5/07. Successful defenses: 6 with 2 wins in non-title matches.

Women’s Flyweight: Satoko Shinashi. Champion since: 2/22/08 (inaugural champion). Successful defenses: 1 with 1 loss in a non-title match.

Shooto (Japan)

Note: Shooto has 4 different fighter classes. The champions listed are the World Champions of Class-A, Shooto’s most elite class.

Flyweight (up to 114.6): VACANT. Determination match between Noboru Tahara & Rambaa Somdet set for 11/23/09 to crown new champion.

Bantamweight (115-123): Shinichi Kojima. 1st reign. Champion since: 10/14/06. Successful defenses: 4 with 1 loss in a non-title fight.

Featherweight (124-132): Masakatsu Ueda. 1st reign. Champion since: 3/28/08. Successful defenses: 3.

Lightweight (133-143): “Lion” Takeshi Inoue. 2nd reign. Champion since: 11/29/08. Successful defenses: 1.

Welterweight (144-154): Willamy Chiquerim. 1st reign. Champion since: 10/30/09. Successful defenses: None.

Middleweight (155-167): Shinya Aoki. 1st reign. Champion since: 2/17/06. Successful defenses: None.

Light Heavyweight (168-183): Siyar Bahadurzada. 1st reign. Champion since: 7/15/07. Successful defenses: None.

Valkyrie (Japan)

Note: Valkyrie is a new all-female promotion created in early ‘09 by GCM, which also runs the Cage Force promotion.

Featherweight: Yuka Tsuji. 1st reign. Champion since: 4/25/09 (inaugural champion). Successful defenses: None. Next defense: TBA.