Source: Marvel Comics
Location: Wherever he can be free to experiment
Threat Assessment: 3.5. He's a genius with genetics. He has created various monstrous beings. He can control them via his ESP box or control rod. His body is in top physical shape.
Limitations: He's um.... fairly mad. Still obsessed with nazi ideology. He's damn ugly.
Personal notes: Perhaps not a classic monster. But geez. He has a headless body with a TV in his chest. That's fairly hard core monsterous. I always felt that Arnim should have spent time with the Headmen a fairly obscure supervillain group. They are all mad scientists who have done weird head things. One is perfectly normal head wise but has grafted it to the body of a gorilla. One has shrunk his bones in trying to be the next Antman (that's raising your sights high, not) and Ruby has cut off her head and replaced it with a polymorphic ruby computer head. Arnim would feel right at home here.