Two villains from Batman’s classic Rogues Gallery get the ’66 treatment in two separate stories! First, Hilda, aunt of Marsha Queen of Diamonds, messes with forces beyond her control and brings forth Solomon Grundy. Then, when False Face goes looking for a shape-shifting formula, he ends up creating Clayface!
(This issue establishes that False Face and Clayface were the same man, Basil Karlo. Throne Labs, which developed the skin regeneration formula, is a nod to actor Malachi Throne, who played False Face in the television series).