Junior dos Santos Almeida (Brazilian Portuguese pronunciation: [ˈʒũnjoʁ dus ˈsɐ̃tus]; born September 12, 1984) is a Brazilian professional mixed martial artist competing in the Ultimate Fighting Championship. Dos Santos fights in the Heavyweight division, under the tutelage of former UFC and Pride Heavyweight Champion Antônio Rodrigo Nogueira and UFC Middleweight Champion Anderson Silva. He is currently ranked as the #2 heavyweight fighter in the world by Sherdog.com, #2 by MMAWeekly, #2 by MMAfighting.com[4] and #3 by FightMagazine.com.

Dos Santos is a practitioner of Brazilian Jiu-Jitsu and currently holds a brown belt. Dos Santos trains his Brazilian Jiu-Jitsu under Antonio Rodrigo Nogueira.

Dos Santos turned professional in 2006 at the age of 21. He fought in small promotions in Brazil, such as Demo Fight, Extreme Fighting Championship, Minotauro Fights and Mo Team League. He won 6 out of his first 7 bouts, with his only loss coming from Joaquim Ferreira, in a rematch.