The Black Knight was a villain with a mountain top castle armed with archers, gangsters, rabbit-sized rats, and trap doors. The crime boss robbed banks to finance his plans of world domination. His plans are foiled by Steel Sterling and apparently dies after his booby-trapped castle explodes. However, he reappears later threatening war with the South American country Brazonia as Dr. Yar and then resurfaces under the guise of Radium King.