Hollywood's Biggest Stars Attend 'SNL's 50th Anniversary After-Party

'Saturday Night Live's 50th Anniversary after-party at the Plaza Hotel in NYC was a huge extravaganza, with some of the biggest celebs on the planet showing up -- including Kim Kardashian, Lady Gaga and Dave Chappelle.

TMZ obtained photos and videos of all the fun, laughter and performances by dozens of celebrities who packed into the ballroom and other parts of the legendary hotel in Midtown Manhattan Sunday night.

Many were photographed in their fancy outfits walking into the event. Of course, Kim K made a huge splash in her silver gown and Gaga looked pretty goth-glam in her get-up.

Others who made grand entrances were Robert De Niro, Jenna Ortega, Halsey, Meryl Streep, Martin Short, Paul Rudd, Paul McCartney, Keke Palmer, Jason Momoa, Alec and Hilaria Baldwin, and Tom Hanks and Rita Wilson.

But, that's not all. Check out our exclusive video showing what happened once the party got started inside.

Here's what we captured ... Larry David chats with Sacha Baron Cohen; Gaga holds court with others surrounding her; James Franco hanging out in a nice suit; Whoopi Goldberg stands near the buffet; Conan O'Brien and David Letterman schmooze with others; Scarlett Johansson dances with Kristen Wigg; and Bad Bunny and Tyga just chilled out.

We also caught Chappelle hosting a band onstage and conversing with Jon Hamm, who busted some moves. At one point, Busta Rhymes grabbed the mic and started telling stories.

Then Brandi Carlile took the mic, and waded into the crowd and convincing Sabrina Carpenter to climb onstage to sing Madonna's "Like a Virgin." Ortega, Wigg and Emma Stone also jumped onstage and did their own little performance.