Superman foes who had some potential (imho)...
- Atoman (Mutual radio 1945; Superman foe) - soldier injected with kryptonite by Nazi scientist determined to get revenge after Germany's defeat; fingers emit green lightning.
- Colonel Future (Action #484)- Col. Edmund H. Future, constructor of the Mechanical Marauders, leader of the C-F Gang.
- Funny Face (Superman #30?) - comic-strip characters brought to life.
- Mala (Superman #65) - evil Kryptonian, accompanied by brothers Kizo and U-Ban.
- Mr. Sinister (Superman #16) - malevolent purple-skinned alien from fourth dimension; speaks in rhyme; uses scientific machinery to kidnap buildings from Earth; high-tech weaponry.
- Wizard of Wokkit (Action #86; Superman foe) - sorcerer.
- The Warlock [The New Adventures of Superman; 1966, Filmation]
- The Sorceror [The New Adventures of Superman; 1966, Filmation]
Some Superman foes who be a better fit for Nightwing (imho)...
- Aesop, Johnny (Action #75) - gang leader who commits crimes based on Aesop's fables.
- The Archer (Superman #13) - Quigley, green-clad famous big-game hunter; uses archery for theft & extortion.
- The Domino (Action #46; Superman foe) - handsome but profligate society playboy Jeff Farnham; dons purple mask and intimidates amusement park
- Hi-Jack (Superman #25) - debt-ridden banker Jack Jackson dons green and purple costume with a jack of spades on his chest to commit crimes.
- Jim Dandy (Superman #107) - dapper leader of criminal gang.
- the Leopard (Superman #20) - Sam Kennedy, publicity man for the Cosmos Circus, dons leopard's-head mask and commits crimes involving big cats.
- Mr. Ohm (Superman #51) - devises a flying electro-magnet to rob armored cars.
- Mother Goose (Action #110; Superman foe) - nursery rhyme-based crimes.
- Night-Owl (Action #53; Superman foe) - scientist; bald, with pointy ears; performs darkness experiments which allow him to see in the dark; has "black light projectors" and pet owl with poison-dipped claws.
- Prankster (Action #51; Superman foe).
- Puzzler (Action #49; Superman foe) - murderous game player, particularly with playing cards.
- Scarlet Widow (Mutual radio 1945; Superman foe) - steals Kryptonite from Metropolis Museum.
- scientist, nameless (Fleischer Studios 5/15/42; Superman foe) - American Indian scientist with underwater base who generates an "electric earthquake" unless Manhattan Island is returned to its native inhabitants.
- Spider Lady (Columbia Pictures 1948; Superman foe) - blonde in black mask and evening gown, has big electrified spider web in hideout; attempts to steal "reducer ray"
- The Tiger Woman (Action #195; Superman foe) - one-eyed bandit leader who is a perfect look-alike for Lois Lane.
- Toyman (Action #64).
- The Water Sprite (Action #82; Superman foe) - Kenneth Darby disguises as hideous green monster as part of elaborate scam.
- Zoltan (Mutual radio 1945; Superman/Batman foe) - runs Zoltan's Wax Museum as listed in phonebook; encases Allied scientists in super-hard "wax-alloy" and smuggles them overseas where they will be forced to work for the Axis.