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- "We remember those who fell during the Last War. Beware Bertron's curse, for he is named Doomsday."
- ―Translated Kryptonian message[src]
At some point in Krypton history, a great war occoured on the planet. During the conflict, the scientist Bertron performed a genetic experiment which resulted in the creation of a deformity with unfathomable power and capacity for destruction. This deformity was later destroyed.
- Judging by the name, the Last War may was the last conflict on a Kryptonian territory before the Battle of Krypton.