Jeremy Graham Horn (born August 25, 1975 in Omaha, Nebraska) is a mixed martial arts fighter. He is one of the most experienced fighters in the sport with a professional record of 80-19-5.

His early martial arts training was under Robert Bussey Warrior International founder, Robert Bussey. Horn earned a RBWI black belt under Bussey in 1992, and spent most of his career with the Miletich Fighting Systems team in Iowa, and is currently training in Salt Lake City, Utah with Elite Performance, the team that he created.

Horn's notable victories include Gilbert Yvel, Forrest Griffin, Dean Lister, Chael Sonnen, and Chuck Liddell. He also fought to a draw against the notable Dan Severn at Extreme Challenge 7 in 1997.

Horn defeated the eventual light heavyweight champion and UFC star Liddell by submission at UFC 19. Liddell later avenged his loss to Horn at UFC 54 in the fourth round, when the fight was stopped after Horn told the referee he could no longer see.

At a September 9, 2006 International Fight League show Horn lost to Matt Lindland in the second round, due to strikes. After the fight Horn announced that he would be taking a break from fighting. He returned from this break when he beat Falaniko Vitale by Split Decision at the IFL Oakland Show.

Horn openly discusses how he often likes to fight more than he likes to win. Although technically very talented, he feels he often lacks the motivation and focus to perform at his best.

He most recently fought his 100th MMA fight, losing to Jorge Santiago by way of a triangle choke at 3:02 of the 1st round.

On January 9, 2008, it was announced by the UFC that Horn would replace Thales Leites in a fight against Nate Marquardt at UFC 81. This was the first time that Horn has fought in the UFC in over a year.

Horn lost to Nate Marquardt in the second round by a standing guillotine choke.

His last fight, against Brazilian Jiu Jitsu ace Rousimar Palhares at UFC 93 in Dublin, Ireland ended in a loss by unanimous decision.