Selina Kyle, The Cat, or Catwoman, debuted in 1940 in Batman #1, the same issue that debuted The Joker. Created by Bob Kane and Bill Finger, Catwoman appears as a cat themed cat-burglar (clever) wielding a whip. A femme fatale character, Selina Kyle seems to have similarities to several film noir actresses, and Irene Adler from Sherlock Holmes.
Her original origin cast her as a former flight attendant with amnesia who began a life of crime. Later stories have her recant this statement, admitting she lied. In 1987 Frank Miller rewrote the origin, casting Selina as a reformed prostitute, turned cat burglar. In Jeph Loeb's Long Halloween/Dark Victory saga, there is a strongly hinted, but never fully revealed relationship between Selina Kyle and Carmine Falcone. She believes she is his illegitimate daughter, travels to Sicily to find the truth, but can never find proof.
The femme fatale is a staple of pulp fiction noir, and Catwoman initially was created to fill that role in the darker pulp world of the original 1940s Batman comics. She has always been a female foil for Batman, and even in the original comics she and Batman blur the lines of the relationship between hero and villain.
|Like most women, she can't decide what to wear|
The problem with making Catwoman a hero, and giving her her own title, is the need for an origin, a supporting cast, family members. When she started to become not just a thief is when things started getting silly. I feel like this character would be better off, like the Joker, without an origin story. The best Catwoman stories operate with the premise that no one knows where she came from, and she isn't telling. Part of what makes a femme fatale is the mystery surrounding her.
Personally, I like the Selina Kyle/Catwoman found in Jeph Loeb's stories, and in the Arkham City game, and in the Dark Knight Rises. She is a thief operating under her own set of morals and values, with her own agenda. A villain only in the sense that she does commit crimes, Catwoman doesn't appear to have a psychosis of the sort found in most other Gotham villains, she still has a conscience and aids Batman for the greater good. The mystery surrounding her, where she came from, what her agenda is, and this weird frustrating relationship she has with Batman, which never really becomes a relationship are the best parts of the character, and make her a pretty substantial part of the Batman universe.