Klaus Voorhees

Klaus Voorhees is a Marvel villain who first appeared in 1963 as the Cobra — a criminal who gained serpentine agility and flexibility after being bitten by a radioactive cobra while working as a laboratory assistant. He became a recurring foe of Thor and later allied with Mister Hyde.

Born in the fertile creative crucible of Stan Lee and Jack Kirby's X-Men #2 back in 1963, Klaus Voorhees is a genuine Silver Age Marvel original whose six-decade publishing history speaks to a staying power that few characters from that era can match. With 77 catalog appearances — including a remarkable 12 collector-recognized key issues — he's carved out a persistent niche across landmark titles like Captain America, Thor, and Immortal Thor, proving himself a recurring fixture in some of Marvel's most storied corners. The company he keeps is telling: pages shared with the likes of Captain America, Thor, and Calvin Zabo place him squarely in the thick of Marvel's action, rubbing shoulders with gods and legends alike. If you're building out your Silver Age Marvel knowledge or hunting meaningful keys, Klaus Voorhees is exactly the kind of deep-cut discovery that makes this hobby endlessly rewarding.