'Eastbound & Down' -- Marilyn Manson Looks Strangely Normal In TV Cameo Role

Go ahead ... take a good look.

That's Marilyn Manson -- AKA Brian Hugh Warner -- getting all actor-y on the set of the TV show, "Eastbound & Down" ... where he's shooting a cameo role this week. This is his intense look.

Manson is a huge fan of "EB&D" ... and has reportedly been lobbying the producers for the last couple of years to cast him in the show ... and it finally paid off. But he must have seriously confused the makeup people on the set ... since he arrived looking, well ... pretty dang normal.

This is the HBO comedy's 4th and final season. No word on when Manson's episode will air.

But he's ready for his closeup.