Dr Harleen Frances Quinzel or Harley Quinn was initially introduced as a love interest and sidekick of popular DC villain Joker. She was a psychiatrist who worked as an intern in Arkham Asylum who was treating Joker but she fell in love with him and was turned.
She appeared frequently in cartoons and comics as the accomplice and lover of the Joker. Eventually, she became a cult favourite of DC fans and started getting her own stories and comic books.
She was initially criticised for being an ambitious woman who sacrificed her autonomy to an abusive relationship.
However, in other stories, she had left the toxic relationship with Joker and began her role as an anti-hero who wants to give up crime.
In other comics, Harley was teamed with anti-heroes Poison Ivy and Catwoman and formed 'Gotham City Sirens'. Harley is regarded as one of the most profitable women in DC comic books and most popular comic book characters of all time.
Oscar-nominated actress Margot Robbie portrayed her in 'Suicide Squad' series and her performance was well-received. She received her own movie 'Harley Quinn: Birds of Prey' which opened to strong reviews.