Trivia

Gruenwald had a detailed knowledge of Marvel's older stories, and he often revived and revamped underused characters.

As a writer, Gruenwald created the fictional organization "Scourge of the Underworld", depicted as a team of assassins which targets super-villains as victims and ambushes them when their guard is down. He used this plot device to get rid of villains who he viewed as redundant, ill-conceived, or largely outdated.