He is a scurvy pirate mad scientist described himself as the "Greatest genius in the Never World", developing various complex mechanical devices, commonly based on sea animals, with the long-term goal of taking over the Never World.
Doctor Undergear is a short-tempered, ego maniacal, raucous and pompous evil mastermind genius. He has all the qualities of a classic mad scientist: he looks, talks, and dresses like a bad guy and possesses the psychotic sense of self-entitlement that urges him to conquering the world, the destruction of his enemies or both. A would-be tyrant, he has a hunger for power and desires as well attention, adulation and a little respect.
- "The Island of Doctor Undergear" (First appearance)
- "Shark Attack!"
- "The Legion of Pirate Villains!"
- "Captain Hook's Last Stand!" (cameo)