Lady Satan is a freelance agent.
By freelance I mean she is not officially associated with any organization as none are ever mentioned. Still, in her second adventure, she is given a secret message with orders so she had to working with someone else - who, we never know. We do know from the beginning, though, that she is "a strange, mysterious woman [who] dedicates her life to ferret out the secrets of the enemies of democracy and to turn these secrets over to the nations engaged in a death struggle to keep the light of liberty aglow. This weird, swift striking character is known as .... Lady .. Satan."
At the start of WWII, the woman who would become Lady Satan is on a cruise ship heading from Europe to New York along with her fiancée. According to a statement by him, the couple were to be married when they reached America. The fact that the nuptials were to take place in the States is the main reason I postulate that they were Americans. That wedding was never to be, though, as Nazi bombers attacked the ship and he was killed. Floating amongst the debris, a very angry woman vows, "I swear henceforth to devote my life to their destruction. My enemies will feel the wrath of Lady Satan."
What her name was before she took that oath and changed her moniker is never revealed. She somehow managed to return to the mainland and began her personal crusade against the tyranny that ordered the destruction of the ship, costing her the life of her love. Regarding names, though, in the first mission we find her on, a German officer she is trying to woo addresses her formally as "Madame Satan" which would indicate she took the last name of Satan instead of just using it as a covername.
Lady Satan does her best work in a slinky red evening dress, complete with a red mask covering her eyes. With her deep black hair, it makes for a very alluring sight, all the better to lure in and destroy her enemies. She is also seen adding a cape with a cowl over the dress which does add a nice amount of flair to her actions.
Quite athletic and fearless when it comes to dangerous stunts, she is adept at hand-to-hand combat and if her fighting skills are not enough, she does have a special gun that can discharge chlorine gas to help her escape.
There are only two recorded adventures of Lady Satan but considering how some ordinary soldiers seem to know who she is and express relief that she had survived a harrowing mission, she apparently has been busy.
Now, jump ahead four years, many months after the end of WWII.
Lady Satan is a fighter of evil.
She is a beautiful woman who favors red evening dresses, a (red or black) eye mask, and often a red cape with a cowl, lives for the chance to fight evil ghosts and phantoms and vampires and werewolves and anything else that goes bump in the night. She mentions in her first recorded adventure (in this persona) that she might be "the only person in the world today who is a master of the art of Black Magic" which is why she is called Lady Satan.
Exactly where she lives is not known but it is obviously in the States and she is by no means unknown in the region. According to the police in one story, Lady Satan's address and phone number were closely guarded secrets but the desk sergeant knows how to contact her. In the next adventure, a lady needing help calls the local newspaper asking them to contact Lady Satan for help and she responds immediately.
[Even more odd than everyone she meets calling her Lady Satan, which as a masked crimefighter is not so unusual (ala Batman and Catman) but in one adventure a very old friend who appeals for her aid calls her Lady Satan and seemingly has done so for some time.]
Besides her athleticism and her keen investigative skills, Lady Satan has several extra tricks to help her in her line of work. One is "Xanda Powder" which can apparently do miracles - it certainly can change werewolves back to human form. There there is the urn containing something given her by a Tibetan lama which can summon the Shadow People who can ferret out bad guys. Finally, she mentions once that she has the strength of 20 men which comes in handy for pulling chains attached to walls.
While one of the people this Lady Satan goes against is a werewolf building up an army of young wolves, the other baddies are human in nature and just plain greedy, although she did need the help of a ghost to uncover one nefarious plot. This tends to make her seem more of a "occult detective" complete with an apparently old adage:
Death by Fright,
Face is White.
Look for Clue
When Face is Blue.
Is there one Lady Satan who, when the fight against the tyrants came to an end, chose a different enemy to fight? Is there a second Lady Satan with her own unspoken origin who has some nifty skills and tools to use in her crusade against a different kind of evil? I do not know. They look the same. They dress the same. They act the same. Strong evidence pointing to the former but no definitive proof.
And then comes the early 70's!
The year 1974 brings us Anne Jason, a beautiful 23-year old black woman just graduated from Vassar and ready to take on the world. What she gets, though, is a change no one expected, one that will give her the title of Lady Satan and an excursion into the realm of the underworld and a meeting with the Devil himself.
Ms Jason gets mention here not because there is any possibility she is at all connected with the person(s) above but because she will use, or have used for her, that same name and when reading about Lady Satan, it is good to know which one is being mentioned. This Lady Satan is not the other.
And on to the 2010's.
Bit of a leap but a Lady Satan from the 30's, dressed in a sleek red dress with a red cape and a cowl, wearing a eye-mask, is joining a group of other vigilantes and taking on a particularly nasty lady who is time-hopping and the group after her have to do the same. This Lady Satan is a glib, alluring, and playful woman who happens to have horns on her head. Real one? Unknown.
Note: If the above is not confusing enough, it is important to remember that the Lady Satan(s) we are discussing here is in no way connected with Madam Satan, a very evil character who had her own short run of adventures in the pages of Pep Comics in 1941, starting with #16 and going until #21.