US stand-up comedian Dave Chappelle was attacked on stage on Tuesday during a performance at the Hollywood Bowl in Los Angeles.
Clips shared on social media showed someone running into the star.
Further videos appeared to show the comic apparently unharmed after returning to the stage at the Netflix Is A Joke Festival.
Chappelle faced criticism and protests last year when his Netflix special was accused of being transphobic.
After returning to the stage on Tuesday, the 48-year-old made light of the controversy, suggesting to the audience that the attacker “was a trans man”.
According to ABC journalist Stephanie Wash, fellow comic Chris Rock – who was slapped on stage by Will Smith at the Oscars in March – then came on stage with Chappelle.
US-based British journalist Sharon Carpenter, who was also in attendance, said actor and singer Jamie Foxx joined Chappelle too.
Carpenter said an attacker “lunged” at the comedian as he headlined the event, sending him “flying in the air”.
She said: “It looked like someone was dashing across the stage from the side. He fell backwards on to his back, with his arms and legs up in the air. He was obviously in shock. We were all in shock.
Tuesday’s incident came five weeks after Smith famously slapped Rock on stage at the Academy Awards after Rock made a joke about the actor’s wife, Jada Pinkett Smith.