#4. Andrei Arlovski - ONE FC: Pride of a Nation
Andrei Arlovski's tenure at ONE may have been short-lived, but it helped change the course of history over the next five years.
When 'The Pitbull' arrived to take on fellow former UFC heavyweight champion Tim Sylvia in the ONE circle, the promotion allowed soccer kicks. Crucially, you could only do them if the referee gave you the 'all clear' having deemed the opponent able to defend themselves.
In this instance, Arlovski cracked Sylvia with two big right hands to send him tumbling to the canvas. He did not have the okay to launch soccer kicks, but he did so anyway and booted Sylvia twice. The fight was ruled a no-contest. Afterwards, ONE decided to allow soccer kicks to go ahead unbridled for almost half a decade before banning them in 2016.
After his short-lived outing with ONE, Arlovski went off to fight in the World Series of Fighting (now PFL). A return to form saw him earn his way back to the UFC where he still competes at the age of 42.
He's in action this weekend against Carlos Felipe at UFC Fight Night: Ladd vs Dumont.
#3. Jens Pulver - ONE FC: Pride of a Nation, ONE FC: Rise of Kings, ONE FC: Kings and Champions
Much like his long-time rival BJ Penn, Jens Pulver fought in several different weight classes for the UFC. He was also the inaugural UFC lightweight champion.
After two separate stints competing in the octagon as well as spells with WEC, Shooto and Pride, Pulver returned to Asia to fight in ONE Championship.
Making his debut against the Philippines' Eric Kelly - 'Lil' Evil's ONE tenure did not get off to a good start as he lost via second round TKO in Quezon City. He bounced back in his next bout, which came in round one of the ONE bantamweight Grand Prix.
The American overcame China's Zhao Ya Fei via unanimous decision. In his third and final outing for ONE, he succumbed to a second round D'arce choke from Masakatsu Ueda in the semi-final of the GP.
Despite only going on to fight once more in MMA, Pulver enjoyed a fantastic career overall and boasts an undefeated record in both boxing (4-0) and kickboxing (1-0).