A professional wrestler who appeared in the Jack Black movie Nacho Libre collapsed and died in the ring in front of hundreds of horrified fans.

Wrestling star Silver King, 51, collapsed just moments after he was repeatedly slammed hard into the canvas during a Saturday night “Greatest Show of Lucha Libre” event in London.

Video shows how unaware fans started booing as he stayed down, with the ref counting him out and his opponent, Juventud Guerrera, pretending to protest.

But medics soon raced into the ring as the former WCW star, real name Cesar Barron, failed to get up.

“It seemed to be part of the show at first but then he didn’t get up – and then the medical team was on the stage. Everybody was cleared out,” a member of the audience told the local paper, the Camden New Journal.

Another fan, Roberto Carrera Maldonado, told the BBC that the deathly drama initially looked “staged” like typical wrestling bouts.

“All of us were really shocked – it wasn’t clear what was happening,” he said.

Comedian Jack Black led the tributes with an Instagram post showing the wrestler, who played a villain called Ramses in their movie, puffing up his muscles in costume.

“César González…vaya con dios, hermano.”

WWE star Chris Jericho also shared how Barron mentored him when he started his career in Mexico.

“I was a stranger in a strange land and many locals didn’t want me there, but Cesar and his partner Johnny (the amazing #Texano) always treated me like an equal,” he wrote on Instagram. “Thank you for taking care of me and teaching me to become a better worker Cesar….

And to me, you upgraded to #GoldKing many moons ago.”

Lucha Libre World, which promoted the event at the Roundhouse Theatre, confirmed the star “suffered what we believe was a cardiac arrest” and “sadly passed away.”

A statement from the venue added, “Our thoughts and condolences are with his family, friends and all of the Lucha Libre team.”