Mister Who was born a cripple, and was teased by other kids while growing up. However, he had a keen intellect, and developed a serum that gave him the power to be strong. He used his new found powers to go on a crime spree, stealing art and treasures to surround himself with beauty. The "Solution Z" lets him escape his body's limitations to achieve a number of feats. He can grow to huge sizes, become paper thin, camouflage into a background, turn himself into an exact replica of a person, and regenerate a lost body part. He also has superhuman strength. As Mister Who, he often battled the Green Lantern and Doctor Fate.