Wonder Woman has been rightfully attributed to William Moulton Marston for decades, but his true inspiration and unusual backstory only trickled out more recently, thanks to research by biographers like Jill Lepore and Noah Berlatsky. Moulston's wife Elizabeth Holloway and mistress Olive Byrne were clearly the faces and personalities behind Diana's character—presuming they didn't play a larger role, since Byrne often transcribed Marston, and Holloway's own research influenced her husband's work.
Byrne and Holloway are fascinating women in their own right, but Byrne's mother, Ethel, likely made her own major impression on Marston and his archetypal superheroine. Ethel and her sister, eminent women's suffrage activist Margaret Sanger, were powerhouses during tghe early feminism movement and launched the first American birth control clinic, the American Birth Control League, in 1916, which evolved into today's Planned Parenthood. Both were threatened repeatedly with legal ramifications and spent time in jail on obscenity charges, with Ethel becoming the first woman forcibly fed in jail after a weeklong hunger strike.
Sanger arranged a pardon for her sister, but the plea agreement with New York's Governor forced Byrne to leave activism behind, creating a rift between them. Sanger continued her long career, becoming a feminist icon, while Byrne fell to the wayside of history. Nevertheless, her and Sanger's influence clearly filtered into Olive, and later Marston himself, as Wonder Woman was born in the pages of DC Comics.