Francisco Santos Mir III[4] (/ˈmɪər/; born May 24, 1979), is an American mixed martial artist who competes in the heavyweight division.

[7] Born and raised in Las Vegas, Nevada, Mir began training and competing in American Kenpo at a school owned by his parents, earning his black belt as a teenager.

[10] Mir played fullback and defensive end on the school's football team, which reached the Southern Zone semifinals in 1997.

He won his second fight by triangle choke in the first round, against Dan Quinn at IFC Warriors Challenge 15 on August 31, 2001.

[14] Referee Herb Dean stopped the fight 50 seconds into the first round after Mir broke Sylvia's right forearm with a straight armbar.

[17] An Interim Heavyweight Championship was created while Mir recovered from surgery, which Andrei Arlovski won by defeating Tim Sylvia via first round submission.

[20] In his first bout since the accident, Mir fought 4th degree BJJ black belt and six-time Mundials champion Márcio Cruz at UFC 57: Liddell vs. Couture 3 on February 4, 2006.

Despite the criticism, Mir was subsequently matched with Brandon Vera at UFC 65: Bad Intentions to determine the number one contender.

[24] Mir showed improved striking ability but was quickly stunned by a straight right from Vera,[25] who then dropped him with knees from the Muay Thai clinch.

Vera then secured side control and delivered a number of punches and elbows, forcing the referee to stop the fight at 1:09 of the first round.

While preparing for UFC 140, Mir attributed his poor performance in his initial return bouts to lingering health issues following the accident.

In the fight with Nogueira, Mir showcased vastly improved striking, particularly his boxing, knocking down the Brazilian twice in the first round and once in the second.

In the second round, after being allowed to stand up, Mir landed a combination, ending with a turning right elbow which forced Lesnar to look for a clinch.

After a short period of recovery from the knee, Lesnar pinned Mir up against the cage and delivered multiple unanswered heavy blows to his face, forcing referee Herb Dean to stop the fight via TKO at 1:48 in the second round.

Two months prior to this fight, Mir replaced his striking coach Ken Hahn with boxing trainer Jimmy Gifford.

Mir was expected to weigh 20 to 25 lbs heavier than usual, due to the strength and conditioning program that he had undertaken to improve his muscular frame.

During the fight, Mir stunned Kongo with an overhand left early, dropping him and swarming to secure a guillotine choke victory at 1:12 in the first round.

[49] Mir later created controversy after commenting that he wanted to break Lesnar's neck, so that he would become the first mixed martial artist to die in competition.

[56] Mir defeated Mirko Cro Cop via third-round knockout, earning the win with a knee from the clinch in a largely uneventful fight in which neither fighter was able to deliver any significant offense.

Mir showed improved wrestling by pushing Nelson against the cage, completing a Judo hip throw and securing several takedowns in the third round.

Mir landed several hard knees and elbows from the Muay Thai clinch throughout the bout but was unable to finish the durable Nelson.

[66] However, on April 20, 2012, Dana White announced that Mir would face Brazilian Junior dos Santos for the UFC Heavyweight Championship, replacing kickboxer Alistair Overeem.

[79] Despite being the betting underdog, Mir won the fight via knockout in the first round, dropping Silva with a left hook and finishing him with a barrage of ground and pound.

Referee "Big" John McCarthy immediately stepped in to stop the fight as Duffee face planted onto the mat.

[90] On April 7, 2016, Mir was notified by the U.S. Anti-Doping Agency (USADA) that the sample he submitted the day of the fight tested positive for oral turinabol metabolites.

[92] Speaking in early 2017 Frank Mir opened up to a radio show about retirement rumors indicating he was still interested in actively competing, and a potential comeback.

However, Ayala rallied in the second round and Mir eventually lost by TKO after tapping to punches that caused an alveolar ridge fracture.

[108] However, on March 23, it was revealed that Tarver was pulled from the bout after failing to meet the requirements to compete put forth by the Georgia Athletic and Entertainment Commission.

[109] On November 27, 2021, Mir faced Kubrat Pulev in the main event of a boxing vs MMA card promoted by Triller that featured other UFC veterans.

[118][119] Frank's oldest biological child, Isabella "Bella Mir" Miranda, is also a professional mixed martial artist.