Chuck Liddell is a mixed martial artist and former UFC Light Heavyweight Champion.

He has an extensive striking background in Kempo, Karate and Kickboxing, as well as a grappling background in collegiate wrestling and Brazilian jiu-jitsu. A professional competitor from 1998 until 2010, Liddell had 23 fights in the UFC; along with Randy Couture, he is widely credited with bringing MMA into the mainstream of American sports and entertainment. On July 10, 2009, he was inducted into the UFC Hall of Fame.

Liddell announced on April 14, 2018, that he was coming out of retirement to target a third fight with Tito Ortiz. The fight took place on November 24, 2018 under Oscar De La Hoya's Golden Boy Promotions. Liddell lost the fight via knockout in the first round.

Liddell was born in Santa Barbara, California. He was raised by his single mother and his maternal grandfather, the later teaching Liddell and his siblings boxing techniques from a very young age. Liddell began studying Koei-Kan karate at the age of 12 (the tattoo seen on his scalp reads "Koei-Kan"). Liddell was a four-year starter on the football team at San Marcos High School, playing center and linebacker while also excelling at wrestling. He became a Division I wrestler at California Polytechnic State University, San Luis Obispo and graduated with a Bachelor of Arts Degree in Business/Accounting in 1995.

Liddell has an extensive striking background in Kempo, Koei-Kan karate and kickboxing, as well as a grappling background in collegiate wrestling and Brazilian Jiu-Jitsu. Liddell holds an amateur kickboxing record of 20 wins and 2 losses, with 16 of his wins coming by way of knockout.

Liddell finished his career with the second most knockouts in UFC history, behind Anderson Silva. Liddell had 23 fights in the UFC, and along with Randy Couture, is widely credited for bringing mixed martial arts into the mainstream of American sports and entertainment.

On July 10, 2009, he was inducted into the UFC Hall of Fame.

Liddell made his UFC debut in 1998 during UFC 17 in Mobile, Alabama, with a decision victory over Noe Hernandez. In his next bout, he faced the legendary Brazilian fighter, Jose "Pele" Landi-Johns, at a bare-knuckle IVC event in Sao Paulo, Brazil. Despite being a heavy underdog in his opponent's home country, Liddell dominated the vale tudo fighter and won via decision. After a technical submission loss to top contender Jeremy Horn shortly after, Liddell began establishing his reputation as a top contender with dominant victories over Kevin Randleman, Murilo Bustamante, Vitor Belfort, Amar Suloev, Jeff Monson, Renato Sobral and Tito Ortiz. Liddell was also the first UFC fighter currently on the roster to go fight in Pride, where he represented the organization against fellow kickboxer Guy Mezger, knocking him out in one of the most exciting fights of his early career.

By 2002, Liddell was considered the #1 contender for the UFC Light Heavyweight Championship, with growing popularity and support from his fans. The UFC tried to arrange a title bout with then-champion Tito Ortiz, but Ortiz cited scheduling conflicts. To force Ortiz's hand, they created an interim light heavyweight championship and matched Liddell with Greco-Roman wrestler and former heavyweight champion Randy Couture at UFC 43. Couture neutralized Liddell's hooks with straight punches and eventually gained full mount and forced a referee stoppage due to a barrage of punches.

After his defeat to Couture, Liddell entered the Pride 2003 Middleweight Grand Prix tournament as the official UFC representative. After defeating Alistair Overeem in the first round of the tournament, Liddell was eliminated by Quinton "Rampage" Jackson.

Returning to the UFC, Liddell was once again put in contention for the light heavyweight title, preparing for a match with former champion Tito Ortiz. The two met in UFC 47 on April 2, 2004, in Las Vegas. In the second round Liddell landed a flurry of punches that dropped Ortiz and led to a TKO victory.

In early 2005, Liddell was a coach on the inaugural season of The Ultimate Fighter. Liddell coached Team Liddell, while then UFC Light Heavyweight Champion Randy Couture coached Team Couture.

In April, 2005, at UFC 52, Liddell fought Randy Couture again for the light heavyweight belt. Liddell knocked Couture out, making him the new UFC Light Heavyweight Champion.

Liddell was scheduled to defend his new title against longtime veteran Jeremy Horn, at UFC 54; Horn had given Liddell his first loss. Liddell dominated with aggressive punches, causing knockdowns in several rounds. Liddell won the fight via TKO in the fourth round after Horn informed the referee that he could not see.

In February, 2006, at UFC 57, Liddell faced Randy Couture in a rubber match. In the second round Liddell knocked Couture out to retain the light heavyweight championship belt. After the fight, Couture announced his retirement from mixed martial arts.

In Liddell's next defense, at UFC 62 in August, 2006, Liddell would best Renato "Babalu" Sobral, who he had defeated nearly three years prior. Seconds after the fight started Sobral came running forward throwing punches, Liddell was moving backwards landing big punches, a right uppercut was the final hit in the onslaught ending the fight at 1:35 of the first round.

In what was the most financially successful UFC event up to that point, Liddell fought a rematch with Tito Ortiz at UFC 66, which took place in December, 2006. Liddell defeated Ortiz via TKO in the third round to successfully defend his light heavyweight championship for a fourth time. It was later revealed that Liddell tore his MCL prior to the fight. In addition, during the fight he popped the tendon out on the middle finger on his left hand.

In his fifth defense, Liddell would lose the title at UFC 71 in May, 2007, in a rematch with Quinton "Rampage" Jackson. Liddell was knocked down by a right hook less than two minutes into the first round and was unable to defend himself against Jackson's strikes on the ground, resulting in a knockout victory for Jackson.

In the main event of UFC 76, Liddell faced Keith Jardine, losing a close split decision, the first consecutive losses of his career.

Liddell met Wanderlei Silva at UFC 79. Liddell defeated Silva via unanimous decision, out-landing Silva with harder, more efficient punches and getting two takedowns later in the fight. Both fighters were awarded "Fight of the Night" honors. This fight was voted 2007's Fight of the Year at the first annual World Mixed Martial Arts Awards and ultimately was Chuck Liddell's final victory in MMA.

In September, 2008, Liddell fought Rashad Evans at UFC 88. Liddell was defeated 1:51 of the second round by knockout.

Liddell's next fight was against the 2005 Pride Middleweight Grand Prix Champion Mauricio "Shogun" Rua at UFC 97 in April, 2009 in Montréal.

Liddell was defeated by Rua due to punches late in the first round resulting in a technical knockout. After the fight, Dana White declared that Liddell would retire from fighting.

In June, 2010, Liddell faced Rich Franklin at UFC 115 in Vancouver, Canada. Liddell suffered his third consecutive knockout defeat.

With the opinions and considerations of his family and friends in mind after losing three consecutive fights by knockout, Liddell decided to end his fighting career on December 29, 2010. At the UFC 125 press conference, Liddell announced his retirement and stated he would be taking the position of Vice President of Business Development within the UFC. Liddell was visibly emotional at the announcement, acknowledging his retirement and an end to his fighting with words of farewell: "Most of all I want to thank my fans and my family. I love this sport and I'm excited to go to this new stage in my life and keep promoting the best sport in the world, the sport I love... now that I'm retired." 

Liddell is currently sponsored by Iceman Fight Gear.  He also is an advertising spokesman for Miller Beer and Duralast Brakes.

Liddell was one of 16 people to compete on Season 9 of Dancing with the Stars. He and professional dance partner, Anna Trebunskaya got 11th place in Week 4.

Liddell came out of retirement for his third fight with Tito Ortiz on November 24, 2018 under Oscar De La Hoya's Golden Boy Promotions. Liddell lost the bout via knockout in the first round.

On March 3, 2020, Liddell announced that he retired from mixed martial arts again.