On Earth One, Ray Salinger was a serial killer, whose first victim was a 15 year old girl named Amanda Grant. From then on he became obsessed with girls who were Amanda's age. He would kidnap them, tie them up, give them a birthday cake that said "Happy Birthday, Amanda", tell them to "Make a Wish, But don't tell anyone." and then kill them. He kept all his victims bodies in the basement of Arkham House. At some point he escaped from the Krane Institute and became employed by Mayor Oswald Cobblepot, as a hitman and was paid in little girls.
Birthday Boy was created by Batman: Earth One writer Geoff Johns, and artist Gary Frank.
Major Story Arcs
Batman: Earth One
For more information see: Batman: Earth One
Birthday Boy, was ordered to kill Jacob Weaver, and payment was Barbara Gordon. Before Birthday Boy could kill her she fought back given, Batman, and her father time to find her. Batman used his cape to suffocate Birthday Boy and defeated him.
For more information see: Teen Titans: Full Throttle
Birthday Boy is seen as one of Robins captured villains.