Mary Dahl was born with a rare disorder which caused her to never grow beyond that of a toddler. But her mind did advance just as any other person would and she became an actress. She was the star in the television sitcom Baby Doll and was very successful. However, the series eventually dwindled in popularity and she left the show after she felt she was being overshadowed by a new character added to boost ratings.
She tried to continue her acting career but her physical appearance held her back from great success. Additionally, having to forever be in the body of a child weighed on her mental condition as she could not have normal relationships.
Baby Doll was created by Paul Dini for Batman: The Animated Series. She first appeared in the episode Baby Doll.
Major Story Arcs
Baby Doll began her criminal career by kidnapping the original cast of her television show, wanting her family back so she could be happy again. She also planned to kill the actor who caused her to leave the show. She was thwarted by Batman and Robin.
Later, she attempted to have a normal life and got a job but became infatuated with Killer Croc. She felt he was a kindred spirit in that he was an outcast and together they started criminal activities. But once Baby Doll found out that Croc did not share her feelings, she attempted to kill him and herself along with Gotham City by blowing up a nuclear power plant. She was once again stopped by Batman and Batgirl and taken into custody.
Batman: White Knight
Baby Doll can be seen with other villains like Killer Croc, Ventriloquist and others under Jack Napier's mind control using Mad Hatter's tech to rampage in the the poor Backport District. How much of her history, if any, is similar to her story in the animated series is unknown.