Joker Jr. was born on Cygnus 4019, where his planet's entire civilisation is based around watching newsfeeds of Earth, namely it's superheroes. His friend Rex Luthor formed The Gang comprised of Joker Jr. and others who wanted to become like the super-powered individuals from the newsfeeds. At some point Joker Jr's parents were murdered by Rex in an attempt to turn him insane like the Joker on Earth, however this failed. Later Rex doused Joker Jr. with chemicals, giving him the physiology and appearance of the Joker.
Adventures of the Super Sons
The Gang stole a ship, enabling them to travel to Earth, where they captured Robin and the Puppeteer. Using the Puppeteer to capture Superboy the Gang then travelled to the Fortress of Solitude, where Rex attempted to kill the Puppeteer, due to him being of uncertain loyalty. However Superboy, overcoming the Puppeteer's control, jumped and took Rex's shot. Joker Jr. took Superboy into Robin's cell while Puppeteer was killed by Rex. Joker Jr. explained the Gang's origins and that he wasn't on Rex's side, asking the Super-Sons to intervene. Joker Jr. then released them from their cell and left the ship in a landing pod. Rex found out about Joker Jr's disloyalty and sent Ice Princess and Kid Deadshot to retrieve him.
- Tactical Analysis
- Hand-to-Hand Combat (Basic)
- Indomitable Will
- 12 Appearances of Joker Jr. (Prime Earth)
- 7 Images featuring Joker Jr. (Prime Earth)
- 1 Quotations by or about Joker Jr. (Prime Earth)
- Character Gallery: Joker Jr. (Prime Earth)