A random dude crashed the stage at the BAFTAs — where Christopher Nolan and other ‘Oppenheimer’ heads were after a major win — and now … the showrunners are pissed.

This awkward moment went down Sunday during the big British award show — the Oscars, basically, for the UK — and it happened right at the end of the show when ‘Oppenheimer’ won Best Film and a bunch of cast and crew members went up to accept.

CN obviously went up, as did Cillian Murphy and other producers for the film … but there was one straggler who ran up onstage well after them — and he definitely didn’t belong.

The guy stood out like a sore thumb, just quietly standing in the back of the group and not batting an eyelash — maintaining his composure and keeping up with the façade. Nobody said anything about him being there either … including Cillian, who was right next to him.

The acceptance speech came and went, and this prankster didn’t really cause much of a scene at all … but that’s not to say the BAFTAs people weren’t angry, ’cause they were.

A rep for the org says … “A social media prankster was removed by security last night after joining the winners of the final award on stage — we are taking this very seriously, and don’t wish to grant him any publicity by commenting further.”

They don’t name him, but he’s pretty easy to find online — dude goes by the name of Lizwani … and he does this crap pretty often. He’s slinked his way into a number of award shows in Britain over the years … and often documents it on his social channels.

No harm, no foul … well, actually — the BAFTAs clearly feel very differently about that. 😅