Comic-Con took place over the weekend, and we're celebrating all the geeky fun. Both celebrities and cosplayers are a common sight at the event, and sometimes the two collide when a star decides to channel a famous character — be they a famous figure in geek culture or a character that they've played themselves. While Tom Hiddleston dressed up as his Avengers character Loki in 2013, Mark Ruffalo  cleverly disguised himself with a mask at New York Comic-Con  last year. Keep scrolling to see all the celebrities who not only showed up but dressed up!
— Additional reporting by Maria Mercedes Lara, Maggie Pehanick, and Kelsie Gibson
The Batman v Superman actor pulled a fast one on the Suicide Squad cast when he posed for a picture with Will Smith  in disguise at Comic-Con in 2016.
For his first Comic-Con in 2014, Daniel Radcliffe  disguised himself as Spider-Man to walk around and mingle with guests. Daniel told MTV that his costume worked and that he wasn't recognized by anyone. "I was just going around doing poses," Daniel said. "It was awesome."
Seeing as how he previously played geek god Doctor Who, Matt Smith is something of an icon at Comic-Con. So, how can he get onto the convention floor without instantly being mobbed by fans? In 2013, the actor dressed up as Bart Simpson to play around with Doctor Who fans. Surprisingly, no one recognized him or paid him much attention, but the whole thing was captured by the BBC cameras. Watch above.
Game of Thrones star Masie Williams got into the Comic-Con spirit in 2014 with not one but two disguises. First, she dressed up as the ever-popular Spider-Man and later changed into a Guy Fawkes mask. After she left San Diego, Masie asked fans, "Did you see this girl?"
Back in 2011, a year before the Spider-Man reboot hit theaters, Andrew Garfield was in costume and ready to go.
Andrew Garfield (Again)
After the release of The Amazing Spider-Man, Andrew Garfield dressed up in his real Spider-Man at Comic-Con in 2012.
The Hobbit director Peter Jackson tricked fans at Comic-Con in 2014 when he dressed up as an Evil Jester. Afterwards, he wrote, "I had a fun day at Comic Con walking among you all. Did anyone see the Evil Jester? Some of you did because you asked him to pose for pics!"
In 2010, Will Ferrell  dressed up as his character, Megamind, to promote the similarly named film.
One of the most contentious points of Veronica Mars is whom Veronica will end up with. At Comic-Con in 2013, the cast decided to have a little fun.
Ryan Hansen got in on the action too.
In 2013, Simon Pegg mixed his Shaun of the Dead ensemble with a Star Wars helmet to walk the convention floor while incognito. Simon said he was "hiding in the light" with his outfit.
Former Hills star Audrina Patridge  embraced her inner geek when she dressed up as Mystique from X-Men at the 2014 convention.
Bryan Cranston and Aaron Paul
The two Breaking Bad stars stepped out in full hazmat suits at Comic-Con in 2012.
Bryan Cranston (Again)
At Comic-Con in 2013, Bryan Cranston really got into character with a creepily realistic Walter White mask.
Mythbusters star Adam Savage spent 10 years working on this Alien spacesuit to wear at Comic-Con in 2014. He wasn't recognized when he walked the floor  in his extreme getup, but he did admit that the suit was incredibly hot inside.
Jaden Smith got a second use out of the white Batsuit he wore to Kim Kardashian and Kanye West's wedding  when he attended Comic-Con in 2014.
The Cast of It's Always Sunny in Philadelphia
Yep, back in 2011, the whole cast dressed up as their alter egos from the show!
Tom Hiddleston wasn't shy at all about slipping into the character of Loki for 2013's Comic-Con.
The Hulk himself, Mark Ruffalo , took to 2015 New York Comic-Con in a creepy old man mask. It's legitimately terrifying.
Jared Leto  sneakily wore this bizarre baboon mask for New York Comic-Con in 2015.