Calvin Zabo

Calvin Zabo was a corrupt physician obsessed with the legend of Dr. Jekyll and Mr. Hyde. After synthesizing his own chemical formula based on that story, he transformed into the brutish, super-strong criminal known as Mister Hyde.

Few villains can claim a Silver Age pedigree forged by Stan Lee and Jack Kirby themselves, but Calvin Zabo made exactly that entrance in Journey into Mystery #110 back in 1964 — and he's been a thorn in Marvel's side ever since. Over six decades and 104 catalogued appearances, this enduring figure has haunted the pages of Captain America, Avengers, and Thunderbolts, sharing panel space with heavyweights like Thor, Captain America, and Spider-Man. With six key issues to his name and a publishing history stretching all the way to 2026, Zabo is the kind of deep-cut Marvel mainstay who rewards the collector willing to dig in — a genuine piece of the House of Ideas' Silver Age foundation still making waves today.