Birthday Girl is one of the numerous superheroes of Great Britain that frequents the Time in a Bottle, a London pub catering to Britain's superhero and supervillain community.
When the Joker began his attacks on British heroes, she and the Black and White Minstrels were able to stop one of the Joker's mind controlled minions. When she discovered that Death Dinosaur and other British villains were reacting to the attacks, she contacted the Knight and Squire to warn them about the villain's involvement. She was present with many other British heroes when the Knight called for a volunteer to help get a message to the Joker's captive, Jarvis Poker.
- Psychokinesis: Birthday Girl appears to have an ability to control small helium filled balloons in her presence. Several balloons are usually in found suspended in the air around her.
- Hand-to-Hand Combat (Basic): Birthday Girl is a competent at hand-to-hand combat.
- Wrestling: She was capable of wrestling one of the Joker's mind controlled minions to the ground.
- Birthday Girl is always nude, hence her name: in British slang terminology, she is wearing her 'birthday suit'.
- In her initial appearance as a background character in the pub of Knight and Squire #1, her hair was blond. When she became a supporting character in Knight and Squire #6, her hair was black.
- 2 Appearances of Birthday Girl (New Earth)
- 1 Images featuring Birthday Girl (New Earth)
- Quotations by or about Birthday Girl (New Earth)
- Character Gallery: Birthday Girl (New Earth)