Marlon Wayans Sued -- I Ain't No Cleveland Brown Lookin' N**** ... Says Actor

Marlon Wayans uncorked what might seem like a hysterical comparison between an actor and Cleveland Brown -- but the actor's not laughing ... TMZ has learned he's suing Marlon for racial discrimination and harassment.

Pierre Daniel says he was hired for a part in "A Haunted House 2" -- written and produced by Marlon -- and last September Marlon posted a side-by-side pic of Daniel and the animated character Cleveland Brown on social media. The pic was captioned, "Tell me this n***a don't look like ... THIS N***A!!! Ol Cleveland Brown ass lookin."

Honestly, seems to be a slight resemblance -- but in his lawsuit, Daniel says Marlon wasn't cracking a joke ... he was essentially cyber-bullying.

Daniel says Marlon's post was racially motivated and mocked his appearance, especially his afro ... according to the docs filed today, and obtained by TMZ. Daniel also accuses Marlon of leering at him and rolling his eyes.

The lawsuit does not say where any of this went down -- but Daniel says the comparison seriously injured him by causing "shock, pain, discomfort and/or anxiety" ... and as a result he can no longer work as an actor.

He's suing Marlon and the movie's production company for unspecified damages. We've reached out to Marlon's camp, but no word back yet.