Is it permissible to laugh when a comedy series mocks a certain character, and is that considered backbiting (Gheebah)?

Perhaps the questioner means that the viewers mocked and ridiculed one of the actors in the series. If that is the case, then this ridicule either targets the actor himself, in which case it falls under the definition of backbiting (gheebah), or it targets the fictional character he plays, in which case it does not fall under this definition because it does not refer to a specific person, and there is no backbiting except against a known individual.