Alistair "Demolition Man" Overeem is one of the world’s most accomplished martial artists, and one of the few men to simultaneously maintain successful careers in the top echelons of both mixed martial arts and international K-1 style kickboxing. Overeem has fought many of the best fighters MMA has to offer, including memorable scraps with “The Iceman” Chuck Liddell, Mauricio “Shogun” Rua (twice), Antonio Rogerio Nogueira (twice), Vitor Belfort (twice), and others. However, he tends to get lazy on defense, as he was knocked out by Rua (twice),  Nogueira (once), Liddell, Ricardo Arona, and Sergei Kharitonov, as well as submitted by Fabricio Werdum. The Liddell and Khaitonov losses were especially showing as Overeem was winning early before leaving himselft open to unnecessary punches.

Overeem is particularly dangerous in the early goings of a bout, where his extraordinary power, 6’5” frame and world-class technical striking ability make him difficult to engage. An aggressive fighter, Overeem is comfortable moving in and striking first in exchanges, and has won many fights in the early goings with heavy combinations. He is also a skilled grappler with a particularly dangerous Guillotine Choke. His brother Valentijn "The Python" Overeem is also a notable fighter, who was a Rings: King of Kings finalist and submitted UFC Hall of Famer Randy Couture. 

Overeem’s weakness in his career in Pride was his tendency to gas in the later stages of a fight, and some believe he could be made to wilt mentally under heavy pressure brought by a fighter with a high pace, like “Shogun” Rua. However, Overeem typically fought in Pride’s 205 lb. division, which may not have been his optimal weight class. Since his move up to heavyweight in California’s Strikeforce promotion, Overeem has gained substantial size and muscle, which helped him seize the heavyweight title in 2007. However, it is questioned by many how he gained so much mass, as he now weighs in close to the 265 limit, and most of his fights took place outside of the United States.

Overeem’s outing against Brett “The Grim” Rogers in Strikeforce in May 2010 was a particularly impressive display by “The Demolition Man,” as Overeem outpaced Rogers a shocking 44-1 in landed blows en route to a first-round TKO victory. He was then place in a rematch with Fabricio Werdum, which he won in a mildly controversial decision, as he slowed his pace after a dominant first round. Werdum's punching output was actually higher the next two rounds, but the judges favored Overeem.

After dispatching of  Werdum in the 2011 Strikeforce Heavyweight Grand Prix, Overeem was suddenly removed from the tournament after making a self determination that he would not be ready for his September match up. He was then subsequently released from the organization and stripped of his title. On December 30th, 2011, at UFC 141, Overeem made his debut with the UFC. He faced off against former heavyweight champion Brock Lesnar, whom had been battling his way back to the octagon following a life threatening bout with diverticulitis. Overeem defeated Lesnar via 1st round TKO. 

Following his win at UFC 146, Overeem was declared the number one contender to the heavyweight title owned by Junior Dos Santos. Unfortunately, the bout, scheduled for UFC 146, never came to fruition as Overeem was suspended by the Nevada State Athletic Commission for elevated testosterone levels. He was replaced in the fight by perennial contender and former heavyweight champion Frank Mir.

Following his suspension Overeem would face off against Antonio Silva at UFC 156. Overeem was favored in this fight and was expected to get a title shot if he could pull off the win. However Silva would pull off another upset and knocked out Overeem in the 3rd round of the fight. Overeem again had a great first round, but stood in front of "Big Foot" not expecting to be punched back. The "Demolition Man" probably won the second round two, but this time was caught by several punches. Early in the third round, Overeem ducked without his hands in front of his face, and was uppercutted out of his championship bout.

Overeem is articulate and soft-spoken outside the cage, though certainly not lacking in confidence. He lives and trains out of Holland. He was next scheduled to face Junior dos Santos, but pulled out of the bout citing a quad injury. He would look to get back in the win column when he faced Travis Browne as the Co-Main Event of UFC on FOX Sports 1. He almost accomplished it landing multiple shots on Browne and it looked like the fight would be stopped. However Browne was able to weather the storm and get back to his feet to eventually land a front kick that would drop The Reem. He would play it safe in his next fight and cruise to a unanimous decision victory over Frank Mir at UFC 169.

On 5 September, 2014, Overeem fought Ben Rothwell at UFC Fight Night 50: Jacare vs. Mousasi 2. Overeem was coming in as a heavy favourite, with Vegas odds closing at -550 Overeem and +425 Rothwell. However Rothwell pulled off the upset by knocking out Overeem in the first round at 2:19. This earned Rothwell the $50, 000 Performance of the Night bonus.

Following yet another knockout upset loss, Overeem was given one last shot against the returning Stefan Struve at UFC on Fox 13. Overeem would go on to dominate the fight knocking Struve out, standing in his guard with ground and pound in the first round. He would make it two in a row when he got the unanimous decision over Roy Nelson at UFC 185, and a third straight victory over perennial contender Andrei Arlovski has earned Overeem a long-awaited shot at the UFC heavyweight title against nascient champion Stipe Miocic at UFC 203.