Mr. D
You haven't seen the last of me Frogger!
~ Mr. D's last words

Mr. D was the sadistic villain of the Game Boy Advance game Frogger: Temple of the Frog. Mr. D took all of Firefly swamp's elements that keep Firefly Swamp alive, so he could witness the swamp's demise. Scattering the elements over 5 countries, the evil Mr. D resided in the Temple of the Frog until Frogger came to eventually restore things back in order. When fought at the end of the game, Mr. D. turns out to actually be a skeletal Grim Reaper. Mr. D is defeated when Frogger uses all the elements against him, and he is sent back to the underworld where he belongs.