Mason Grimshaw was one of the fictional characters created by Jason after he was made Master of the Land of Fiction.

He was an American who was secretly the White Knight's archenemy, the supervillain Doctor Nemesis. After killing the White Knight's sidekick Sparky, he gave up his criminal career and moved to Arandale. Unfortunately, he killed a child while driving drunk and was blackmailed by Mel Joseph. The pressure caused him to snap and become Doctor Nemesis again. He went after his old enemy seeking revenge. After finding him, he started beating him to near death. Rosemary Chambers was able to use her witchly powers to disintegrate Grimshaw before he could kill Powers. (PROSE: Conundrum)

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