General terms:
* Humorist
* Funny person
* Entertainer
* Jester
* Wit
* Clown (can be less formal or even derogatory)
More specific terms:
* Stand-up (for a comedian who performs solo)
* Impersonator
* Satirist
* Comedienne (specifically for a female comedian)
* Comic
* Funnyman/Funnywoman
Informal terms:
* Laugh riot
* Jokester
* Wisecracker
* Cut-up
The best word to use depends on the specific context and the tone you want to convey.