Like every location found on the Beyonder's Battleworld following the events of the first Secret Wars, Leenn was the product of the subconscious mind of the Fantastic Four's Thing,  the Thing had decided to remain on Battleworld  after discovering he could change back and forth between human and Thing forms.  Each of these creations were based off some aspect of Ben's memories or personality, with entirely fabricated backgrounds and origins.  Leenn was inspired by Doctor Doom's native country of Latveria.
According to the people of Leenn it was founded ten thousand years ago following an epic battle between the wizards of Kirithiril and the evil sorcerers of Starnaris. Following their victory they built a castle that resembled Castle Doom to guard the people against future invasion. When the realm of Leenn was later terrorized by the Wizard, they sent their warriors Hanrak and Tarianna to stop him.  They succeeded thanks to the intervention of the Thing, who Tarianna brought back to her home.  Seeking answers as to how this domain could look so much like Latveria, the Thing ventured into the castle. There he clashed with the Wizard again and smashed a device under his protection. Upon smashing the device, the entire city of Leenn and all its people -- with the exception of Tarianna -- vanished from existence. 
- Appearances of Leenn
- Minor Appearances of Leenn
- Media Leenn was Mentioned in
- Location Gallery: Leenn
- Images related to Leenn
- Marvel Staff members who were born in Leenn