The biggest star in UFC history says he's done in the Octagon.

Conor McGregor tweeted Saturday night that he will be retiring from MMA. It was a sudden, unexpected announcement -- and one many thought was insincere. McGregor has tweeted twice before that he was hanging up the gloves but fought as recently as this past January.

Hey guys I've decided to retire from fighting.
Thank you all for the amazing memories! What a ride it's been!
Here is a picture of myself and my mother in Las Vegas post one of my World title wins!
Pick the home of your dreams Mags I love you!
Whatever you desire it's yours ❤️ pic.twitter.com/Dh4ijsZacZ

— Conor McGregor (@TheNotoriousMMA) June 7, 2020

Earlier Saturday, McGregor posted a video of himself training in his garage. Late last month, the former UFC two-weight champion expressed interest in several opponents in the near future. On May 28, he wrote on Twitter that he accepted a proposal for a fight against UFC legend Anderson Silva.

McGregor was once tied to a fight this summer with current top lightweight contender Justin Gaethje. A trilogy bout against Nate Diaz has also been rumored. UFC president Dana White said earlier this week that the best path for McGregor might be to wait and face the winner of Gaethje's title challenge against McGregor nemesis Khabib Nurmagomedov.

Regarding McGregor, White told reporters after UFC 250 on Saturday night that people have been acting strangely lately due to the coronavirus pandemic. But if McGregor wants to retire, White said, then he should retire.

"Nobody is pressuring anybody to fight," White said. "And if Conor McGregor feels he wants to retire, you know my feelings about retirement -- you should absolutely do it. And I love Conor ... there's a handful of people that have made this really fun for me. And he's one of them."

McGregor, 31, famously "retired" on Twitter in 2016 in a dispute with the UFC over traveling to do media for a UFC 200 bout with Diaz. The UFC pulled McGregor from the fight because he wouldn't come to the United States for a news conference. McGregor tweeted April 19, 2016: "I have decided to retire young. Thanks for the cheese. Catch ya's later."

Another retirement tweet came March 25, 2019, in the midst of more jockeying with the UFC. McGregor ended up returning at UFC 247 on Jan. 18, stopping Donald Cerrone via TKO in just 40 seconds.

McGregor (22-4) has just two UFC losses, one to Nurmagomedov and one against Diaz, which he avenged. "The Notorious" became the first UFC fighter to hold two titles in two different weight classes at the same time when he knocked out Eddie Alvarez to win the lightweight belt at UFC 205 on Nov. 12, 2016.

White said "the amount of people that I have gunning at me right now is insane," referring to current UFC beefs with light heavyweight champion Jon Jones and star Jorge Masvidal.

"One of the beautiful things about this sport is: You don't have to fight," White said. "This isn't the NBA or NFL, where you better be at practice, you better show up and do this, you better do that. You don't have to do anything here. And if these guys want to sit out and retire right now or anybody feels uncomfortable in any way, shape or form with what's going on, you don't have to fight. It is all good.

"If that's what Conor is feeling right now -- Jon Jones, Jorge Masvidal, I feel you. It's not like I'm going, 'Holy s---, this is crazy, this is nuts.' Nothing is crazy and nuts right now, because everything is crazy and nuts right now, on a certain level. I totally understand it and get it."