Zack Greenfield, together with his older brother Josh, acquired two dogs that had been part of a LuthorCorp animals testing project. With the aid of a special serum, the dogs were granted superhuman strength. Having access to the serum, Zack and Josh began to use the dogs to commit robberies. However, one of the dogs ran away and was found by Lois Lane. Zack and Josh soon got the dog back, but this got them into conflict with Clark Kent. After committing another robbery and attempting to murder Clark, who was saved by the escaped dog, Zack and Josh were apprehended by the police.



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This character is or was primarily an enemy of Superman in any of his various incarnations, or members of the Superman Family. This template will categorize articles that include it into the "Superman Villains category."

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