You want obscure characters? You got it!
(Unfortunately, many Fawcett, Nedor and Quality characters ‘owned’ by DC are in the public domain now. So, I will try my best to create a derivative work.)
Blue Lama
Blue Lama: 1942, Sensation Comics #68. The Blue Lama is a blue skinned sorceress that was a recurring foe of Sargon the Sorcerer. In addition to her magic powers, in her first appearance, she lead a group of sorcerers to defeat Sargon but the tables were turned. She doesn’t need a revamp; she needs a new opponent…like Zatanna.
Bifröstson (nee Rainbow Man)
Bifröstson: 1942, Action Comics #46. An early recurring foe of the Vigilante and Stuff. He and his gang used the colors of the rainbow and his "Rainbow Globe" for crimes.
The Green Hag (nee The Hag)
The Green Hag: 1948, Doll Man Quarterly #19. Beautiful Patricia Wentworth aka the Hag is in prison and as she's been a model prisoner, she's asked to play a witch in a performance of “Macbeth”. Disguised as a witch and using her knowledge of chemistry, she gases the warden and guards with deadly vapors from the witch's cauldron during a rehearsal and makes her escape. She gives warnings of her crimes through cryptic poems and then uses science to mimic magic to carry them out (such as robot gliders disguised as bats and controlled by a supersonic whistle). NOTE: The story gives the idea that she appeared before but the GCD lists this as a her first appearance. She doesn’t need a revamp; she needs a new opponent…like Batwoman.
The Lightning Bug
The Lightning Bug: 1948, Sensation Comics #76. This female costumed crook is a scientific genius, discovering an electro-magnetic force that she calls "Z-Rays" which she can direct through the combination of her belt and antennae on her cowl. She gives out free radios as part of a hoax, one of which to Sargon's assistant Max. When Sargon touches the radio, it shocks and paralyzes him and the radio flies back to the Lightning Bug dragging him along. There she imprisons him in a vacuum tube to die of suffocation while she and her gang go on a crime spree as the other radios were rigged to explode, killing their owners and leaving their homes open to looting. Sargon breaks free and captures her and her gang. She doesn’t need a revamp; she needs a new opponent…like Batwoman.
Madam Braun (nee Madam Brawn)
Madam Braun: 1941, Police Comics #4. On a spacious farm outside of Windy City, Madam Braun runs her school for female ex-cons. She trains them to be able to outfight two men at the same time, by starting out with four hours of hard work and two hours of boxing and wrestling each day and once conditioned, going in to the real training. There's also regular training on how to shoot, from rifles to tommy guns. And, no smoking. Only Madam Braun is allowed that privilege. When they are ready, they start to take over the protection racket in Windy City, beating up Lefty Goon and his goons in the process. Plastic Man, who is undercover in Lefty's gang, warns Madam Braun of Lefty planning on retaliating. He is promptly captured by her she-devils and fore-warned, they wipe out Lefty's gang when it arrives. Plastic Man is willing to let her off with a warning but she wants vengeance for him ruining her plans. She dies the following issue in the attempt…or not. Note: Her name is either Braun or Braune but this chronicler is uncertain which is correct.
The Mermaiden (nee Scarlet Mermaid)
The Mermaiden: 1941, Flash Comics #19. The Mermaiden is a beautiful blonde woman dressed in form fitting red scaled costume and commits daring robberies at sea. Her “real” identity is Miss Scarlet Wilde, living in a posh apartment building with a doorman named George. She is captured by the King who frightens her with a bunch of mice. She doesn’t need a revamp; she needs a new opponent…like Batwoman.
Ms. Figure (nee The Figure)
Ms. Figure: 1950, Plastic Man #23. The incredibly beautiful and curvaceous Figure is also a genius at mathematics. She uses that combination to become a crime boss and mastermind. She is stopped by Plastic Man.
Ruthless (nee Tigress)
Ruthless: 1938, Action Comics #1. This woman is the leader of a murderous gang of thieves and played up as a master villain that Zatarra is after and is still at large at the end of the story. Even in this adventure, they already had met at least once before. While she had a penchant for tight striped tops, she didn't wear a costume as such, a headband and skirt. She isn't above manhandling the hero, and is the leader of a gang of crooks. Fred Guardineer's bold line art helps to make her really stand out. She doesn’t need a revamp; she needs a new opponent…like Batwoman.
Veda, the Cobra Woman (nee Veda Kane)
Veda, the Cobra Woman: January 1942, Police Comics #6. Slinky Veda was an exotic Indian dancer who married the wealthy American Peter Kane. She then put cobra poison on her lips to kill both Kane and his drunken son with a kiss, in order to gain their fortune. Her plot was foiled by Chic Carter.
In addition to having the kiss of death, Veda kept a huge cobra in her room, that she worshiped as a god. She was said to move like a snake, and at least one observer said that she looked like a cobra (probably because she dresses in a green skin-tight costume and performs for audiences, mimicking the moves of the cobra). She doesn’t need much of a revamp; she needs a new opponent…like Batwoman!