I remember a really great Mister Scarlet story in which several villains team up to form a murder syndicate; the villains were really, really evil and had names like The Thorn and The Clown. Maybe someone knows what comic that story appeared in.
It seems like the golden age heroes fought a lot of scientists and magicians, guys with bald heads or pointy ears or who resembled horror movie monsters, and people that use really horrific gimmicks to murder people. If these characters appeared in a modern comic, they would be considered significant menaces, and would probably comic back in another story and get added to the list of rogues, but in golden age comics these villains were commonplace and usually died in their first appearance, never to return.
Should the Digital Comics Museum add a wiki section to catalog characters?