Junior dos Santos (Portuguese pronunciation: [ˈʒũnjoʁ dus ˈsɐ̃tus]; born 30 January 1984) is a Brazilian mixed martial artist and former professional wrestler who competes in the Heavyweight division.

As a professional wrestler, dos Santos made appearances for All Elite Wrestling (AEW) as a member of the American Top Team stable.

Dos Santos and his two siblings were raised by a single mother, Maria, after his alcoholic father, Sebastian, left the family in the mid-1990s.

Considered a major underdog,[10] he knocked out top contender Fabrício Werdum at a minute and twenty seconds of the first round,[11][12] earning himself a "Knockout of the Year" award.

[13] Returning on 21 February 2009 at UFC 95 he fought promotional newcomer Stefan Struve, defeating him at fifty-four seconds of the first round by knockout.

[14] On 19 September 2009, Dos Santos continued his winning streak and defeated Mirko Cro Cop at UFC 103.

[17] Instead, on 2 January 2010, Dos Santos fought Gilbert Yvel,[18] winning the fight via TKO at two minutes and seven seconds of the first round.

[27][28] On 11 January 2011, the president of the UFC, Dana White, announced that Dos Santos would be one of the coaches of The Ultimate Fighter Season 13, opposite Brock Lesnar.

[29] They were scheduled to face each other on 11 June 2011, at UFC 131,[30] but Lesnar pulled out of the bout due to a recurrence of diverticulitis and was replaced by Shane Carwin.

[31] Dos Santos dominated Carwin and won the fight via unanimous decision,[32] relying predominantly on his boxing skills,[33] but showed more variety in his game by landing a couple of kicks and completing two takedowns in the third round.

[40] Dos Santos was scheduled to face Alistair Overeem on 26 May 2012 at the MGM Grand Garden Arena at UFC 146.

[44] Dos Santos was able to keep the fight standing, showing his superior boxing skills, eventually winning via KO in the second round.

Dos Santos later claimed that he was training so hard prior to the bout with Velasquez that he developed rhabdomyolysis, a (sometimes fatal) breakdown of muscle fibers that releases their contents into the bloodstream, and that the condition affected his performance during the fight.

[63] After a year away from the sport, Dos Santos had the three-years-delayed fight with Alistair Overeem which took place on 19 December 2015 at UFC on Fox 17.

[67] Dos Santos was originally expected to face Stefan Struve in a rematch on 19 February 2017 at UFC Fight Night 105.

[74] On 24 April 2018 Dos Santos was cleared of intentionally using of Performance-enhancing drugs (PEDs) by USADA, after it was determined he had taken tainted supplements which contained hydrochlorothiazide from the compounding pharmacies in Brazil.

[75] Dos Santos returned from his suspension and faced former WSOF Heavyweight Champion Blagoy Ivanov on 14 July 2018 at UFC Fight Night 133.

[86] As the first bout of his new eight-fight contract, Dos Santos faced Curtis Blaydes on 25 January 2020 at UFC Fight Night 166.

[95] Dos Santos outstruck De Castro for most of the bout, but would go on to lose by technical knockout due to a doctor stoppage after suffering a shoulder injury early in the third round.

[101] Dos Santos is scheduled to make his Bare Knuckle Fighting Championship debut against former Aleksei Oleinik on April 4, 2025 at BKFC 71 Dubai: Day 1.

[102] In the summer of 2021, dos Santos began making appearances for the professional wrestling promotion All Elite Wrestling, backing American Top Team head Dan Lambert along with ATT affiliated fighters Andrei Arlovski, Paige VanZant, Austin Vanderford, Dalton Rosta, and Jorge Masvidal.

On the 6 October edition of AEW Dynamite, it was announced that Dos Santos would be making his professional wrestling debut on the 15 October edition of AEW Rampage, teaming with Sky and Page to take on Jake Hager, Chris Jericho and Sammy Guevara (The Inner Circle) in a trios match.