Mar 30, 2012 Joe Warren is a veteran warrior of this sport and one of the best fighters on the Bellator roster. Warren was the featherweight title holder until he ran into the wall that was Pat Curran in March. Frank Mir is an American mixed martial artist, who currently competes in the Bellator MMA Heavyweight division. Before competing in Bellator, he was previously a UFC fighter for 16 years. Mir is a former UFC Heavyweight champion and holds the record for the most fights, victories, and submissions in UFC Heavyweight history.

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• Freire, known as “Pitbull” to fight fans, is currently the only double champion in Bellator. He and his brother, Patricky, both fight for the promotion and share the “Pitbull” nickname. Their tenacity in competition warrants the nickname. Patricio holds two titles—and while awaiting another bout—is calling out UFC lightweights.

When Maycee Barber and Gillian Robertson face off Friday night on the main card of UFC Fight Night: Reyes vs. Weidman in Boston, they'll represent a youth movement that bodes well for the future of mixed martial arts.

Some of the most exciting fighters in the sport, including Barber and Robertson, are younger than 25 years old. A few are already highly ranked contenders and on the verge of title shots. Others are sure to be champions one day.

The UFC itself turns 26 in November and the caliber of athlete emerging onto the MMA scene is only getting better.

Over the past several months, ESPN's panel of insiders has developed a list of the top 25 fighters in the world under 25. Organizations like the UFC, Bellator, ONE Championship and PFL are all represented. The results of that research -- and a compilation of some of the most promising prospects on the planet -- are below. These are the fighters we believe are the best at this moment, without taking into account the potential success of their future endeavors.

1. A.J. McKee (15-0)

Turns 25: April 7, 2020

The crown jewel of Bellator's crop of prospects, McKee has strong bloodlines. His father, Antonio, is a successful veteran of MMA with nearly 40 fights. McKee, 24, is coming off an eight-second knockout of Georgi Karakhanyan in the Bellator Featherweight World Grand Prix first round. The Long Beach, California, native's mix of wrestling, athleticism, power and charisma could make him a future star.

Next fight: Dec. 21 against Derek Campos.

2. Sean O'Malley (10-0)

Turns 25: Oct. 24

When it comes to talent, O'Malley belongs near the top of this list. The 24-year-old Montana native is undefeated and quickly made a name for himself with two wins in the UFC and his charismatic, quirky personality. However, O'Malley is under suspension from the Nevada State Athletic Commission (NSAC) for testing positive for the prohibited substance ostarine. He was suspended by USADA, the UFC's anti-doping partner, last year. O'Malley's Octagon return date is currently up in the air.

Next fight: TBA.

3. Edmen Shahbazyan (10-0)

Turns 25: Nov. 20, 2022

A few years ago, coach Edmond Tarverdyan's fighter Ronda Rousey was the talk of the MMA industry, a supernova who became one of the most dominant champions -- and biggest crossover draws -- in UFC history. Shahbazyan, just 21 years old, is Tarverdyan's latest progeny set for stardom. Shahbazyan, a Glendale, California, native, is 3-0 in the UFC with two straight finishes in under two minutes.

Next fight: Nov. 2 vs Brad Tavares.

T4: Nasrat Haqparast (11-2)

Turns 25: Aug. 22, 2020

The German-born son of refugees from Afghanistan has an indelible fighting spirit. Haqparast, 24, has won three straight in the UFC and most recently scored a violent knockout of Joaquim Silva at UFC Newark in August. Haqparast, who trains out of Tristar Gym in Montreal with the likes of Georges St-Pierre, figures to be a future force in a stacked UFC lightweight division.

Next fight: TBA.

T4: Aspen Ladd (8-1)

Turns 25: March 1, 2020

The UFC entrusted Ladd, 24, with a women's bantamweight title eliminator against former champ Germaine de Randamie in August. De Randamie won via knockout, but it was a testament to how much faith the promotion has in Ladd, who is appealing that stoppage. The California native had three straight wins in the UFC, two coming via finishes. Ladd is still ranked No. 4 by ESPN among women's bantamweight fighters.

Next fight: Dec. 7 vs. Yana Kunitskaya.

6. Maycee Barber (7-0)

Turns 25: May 18, 2023

From the beginning of her UFC career, Barber has made it known that her goal is to be the youngest champion in the history of the promotion. Still just 21 years old, Barber has two years to get that done. Jon Jones was 23 when he won the UFC light heavyweight title in 2011. Barber is currently 2-0 in the UFC with two finishes.

Next fight: Oct. 18 vs. Gillian Robertson.

7. Jimmy Crute (10-1)

Turns 25: March 4, 2021

One of the UFC's best prospects out of Australia, the 23-year-old Crute had a setback in his last fight, falling to ranked light heavyweight Misha Cirkunov on Sept. 14. Perhaps that was too much of a step up for 'The Brute.' But Crute still has two UFC wins -- both by finish -- and a world of potential at 205 pounds.

Next fight: TBA.

8. Song Yadong (14-3, 2 NC)

Turns 25: Dec 2, 2022

Zhang Weili became the UFC's first Chinese champion back in August when she stopped Jessica Andrade to win the women's strawweight title. Song, 21, might be China's next best chance at a titleholder. 'The Kung Fu Monkey' has won seven in a row and is 3-0 in the UFC. In his last fight on July 6, Song earned a $50,000 Performance of the Night bonus for a vicious one-punch knockout of Alejandro Perez at UFC 239.

Next fight: Dec. 7 vs. Cody Stamann.

9. James Gallagher (10-1)

Turns 25: Oct. 24, 2021

Gallagher, 22, rebounded from his first loss by winning three straight, including two first-round submissions for Bellator. Conor McGregor's protégé has taken some of that swagger from his mentor and Bellator has pushed 'The Strabanimal' as a future star. Gallagher seems to have settled in at 135 pounds after starting at 145.

Next fight: TBA.

10. Ricardo Ramos (13-2)

Turns 25: Aug. 1, 2020

It's hard to believe Ramos is just 24 years old, because he's been in the UFC for nearly three years. The explosive Brazilian is 4-1 in the promotion and had one of the best knockouts of 2017, a spinning back fist finish of Aiemann Zahabi. Ramos figures to be a factor moving forward in the bantamweight division.

Next fight: Nov. 16 vs. Eduardo Garagorri.

11. Michal Oleksiejczuk (14-3, 1 NC)

Turns 25: Feb. 22, 2020

One of the most promising young fighters in the light heavyweight division, the 24-year-old Oleksiejczuk started his UFC run unbeaten in three fights before succumbing to an Ovince Saint Preux submission on Sept. 28. Oleksiejczuk, a native of Poland, owns a first-round body shot finish over veteran Gian Villante.

Next fight: TBA.

12. Gillian Robertson (7-3)

Turns 25: May 17, 2020

Quietly, Robertson, 24, has compiled the most wins in UFC women's flyweight history -- four -- by being active and consistent. The red-haired 'Savage' has won two straight and four of five, with every UFC victory coming by finish. Robertson, a Canadian who trains at American Top Team, could be a future title contender.

Next fight: Oct. 18 vs. Maycee Barber.

13. Aaron Pico (4-3)

Turns 25: Sept. 26, 2021

One year ago, Pico would have likely topped this list. And there's still a chance he'll end up being the best of the bunch. Once considered a can't-miss prospect, Pico has lost twice by knockout this year and his MMA record sits at 4-3. Pico is still just 23 years old and his background as a former Golden Glove champion boxer and amateur wrestler who nearly made the Olympics makes him a commodity to still keep your stock in.

Next fight: TBA.

14. Angela Lee (10-2)

Turns 25: July 8, 2021

Lee, 23, hit a snag this year when she moved up to 125 pounds, dropping two fights, including a title bout against Jingnan Xiong. But 'Unstoppable,' the older sister of Christian Lee, rebounded by maintaining her hold on ONE Championship's 115-pound division over the weekend. Lee (10-2) beat Xiong by fifth-round submission in a rematch to retain her title. The Hawaii resident has never lost at 115 pounds and is among ONE's biggest stars.

15. Ismail Naurdiev (19-3)

Turns 25: Aug. 18, 2021

'The Austrian Wonderboy' rebounded from his first UFC loss with an impressive victory over veteran Siyar Bahadurzada on Sept. 28. Naurdiev, 23, is now 2-1 in the UFC and there are high hopes for his future in the welterweight division. Naurdiev might be young, but he's already been a pro for seven years with more than 20 professional fights.

Next fight: TBA.

16. Jack Shore (12-0)

Turns 25: Feb. 6, 2020

The Welsh fighter stormed into the UFC on Sept. 28 with a first-round submission win over Nohelin Hernandez. Shore, 24, has long been considered one of the United Kingdom's top prospects. 'Tank' has won four straight, all by finish, and has gone to decision just once. Shore is the former Cage Warriors bantamweight champion.

Next fight: TBA.

17. Montana De La Rosa (10-5)

Turns 25: Feb. 14, 2020

De La Rosa, 24, had been on a roll with three straight submission victories to start her UFC career before a tough loss to Andrea Lee on June 22. A win there could have put the Montana native into title contention. De La Rosa still has the wrestling -- she was a three-time high school All-American -- and grappling to give her 125-pound peers trouble. And the best is likely yet to come.

Next fight: TBA.

18. Pedro Carvalho (11-3)

Turns 25: Aug. 8, 2020

Fans in the United States were introduced to Carvalho, 24, with his second-round submission finish over Sam Sicilia in the Bellator Featherweight World Grand Prix first round on Sept. 7. Carvalho, who trains with Conor McGregor at SBG Ireland, has won six straight.

Next fight: A title shot in the Bellator Grand Prix quarterfinals in March against Patricio Freire.

19. Umar Nurmagomedov (10-0)

Turns 25: Jan. 3, 2021

Perhaps the next Nurmagomedov to make it big in MMA, Umar is following in the footsteps of his cousin Khabib, the UFC lightweight champion. Although not officially in the league, Nurmagomedov, 23, notched his second consecutive victory in PFL on Aug. 8 with a unanimous decision win over Sidemar Honorio. The Dagestan native is undefeated at 10-0 and could remain in the PFL next year if the promotion adds a bantamweight season.

Next fight: TBA.

20. Thiago Moises (12-4)

Turns 25: March 23, 2020

Moises, 24, has had a rocky start to his UFC career, going 1-2. But the Brazilian impressed with a TKO finish on Dana White's Contender Series Brazil in 2018 and has a bright future. Moises is a former RFA lightweight champion with power in his hands and shins and a smooth ground game.

Next fight: TBA.

21. Jalin Turner (8-5)

Turns 25: May 18, 2020

Known as 'The Tarantula' for his extensive collection of the species of spider, Turner is a unique character. The 24-year-old made a name for himself in the UFC with a 59-second knockout of Callan Potter back on Feb. 9. Turner lost two of his first three UFC fights, but his power, athleticism and range -- he's a 6-foot-3 lightweight -- make him a future force to be reckoned with.

Next fight: TBA.

22. Christian Lee (13-3)

Turns 25: June 21, 2023

Lee got his start in ONE Championship at 17. He's 21 years old now, and he's the ONE lightweight champion, just took home the ONE lightweight grand prix title this past weekend and is one of the most exciting young fighters in MMA. Lee (13-3) has won four straight and it would have been five if not for a disqualification due to an illegal suplex. The Hawaii resident has truly been beaten by only one man: ONE featherweight champ Martin Nguyen.

23. Sabina Mazo (7-1)

Turns 25: March 25, 2022

Mazo, 22, picked up her first UFC win on Aug. 17 after a setback in her debut. The Colombia native, who trains at Kings MMA under legendary coach Rafael Cordeiro, is the former LFA women's flyweight champion and one of the best up-and-coming talents in that division. At 5-foot-7 with a 70-inch reach, Mazo represents a tough stylistic matchup for most at 125 pounds.

Next fight: TBA.

24. Sage Northcutt (11-3)

Turns 25: March 1, 2021

The UFC invested quite a bit in Northcutt, 23, as one of the future faces of the promotion. Dana White discovered him on Lookin' for a Fight and he was signed to the UFC in 2015 -- when he was just 19 years old. Northcutt went 6-2 in the UFC and was on a three-fight winning streak when he left as a free agent for ONE Championship. In his ONE debut in May, Northcutt was knocked out in the first round by Cosmo Alexandre and fractured multiple bones in his face.

Next fight: TBA.

Famous Bellator Fighters

25. Arman Tsarukyan (14-2)

Turns 25: Oct. 11, 2021

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Tsarukyan, 23, lost his UFC debut on April 20 to Islam Makhachev, but he took Makhachev to the absolute limit and it could be argued he should have won the decision. Makhachev is one of the best up-and-coming fighters in the lightweight division. For his second act, Tsarukyan defeated Olivier Aubin-Mercier at UFC 240 on July 27 in another impressive performance.

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Next fight: TBA