Tilda Johnson, aka Nightshade made her first appearance in Captain America #164 (August 1973), created by Steve Englehart and Alan Lee Weiss. After growing up in a poor part of New York City, Johnson discovered she had a natural aptitude for science.

As she got older, Tilda used her extensive knowledge to pursue a career as a criminal scientist. Later on, Johnson teamed up with the Yellow Claw to develop a method for turning humans into obedient werewolf-like creatures. The pair were defeated by Captain America and SHIELD when they attempted to transform a group of convicts into a werewolf army.

Eventually, Nightshade took control of a SHIELD facility. Using a new pheromone, she forced Captain America into a battle with the Falcon, before ultimately being defeated. On a separate occasion, Johnson joined forces with Stiletto, Discus, Man Mountain Marko, and Eel to rob a debutante’s ball. They were all defeated and captured by Power Man and Iron Fist. Nightshade later appeared as the second-in-command of Superia’s Femizons. Nightshade developed a serum to transform men into women which she used on Captain America and Paladin.

Later, while working as a double agent for Superia, Nightshade got involved in a scheme with Dredmund Druid. They used a serum to transform Captain America and the people of Massachusetts into pseudo-werewolves. Nightshade is best known for turning Captain America into the Cap Wolf for a brief period of time.