King Tut famously originated on the Batman '66 TV series, so his automatic association with camp means that, on the surface, he seems like a poor fit for the grim streets of Gotham. Think about it, though. He's an Egyptologist who murders Gotham's elite and, at times, believes himself to be the literal reincarnation of a pharoah. Something about that is definitely creepy, and with a bit of a makeover it could easily work on the show. He could even show up initially as merely an expert, or even a history tutor to, say, Bruce Wayne.