Marvel's superheroes are a multifarious group, running the gamut of humanity. While they don't always agree on everything, there's one rule that is pretty standard among the superheroes of the world - no killing. Superheroes hold themselves to a higher standard and not killing is part of that standard. However, not every hero follows this rule. Marvel pioneered the violent anti-hero, and since then many heroes have come around who will kill their enemies.
Source：https://www.cbr.com/deadliest-marvel-characters-ranked-kill-count/
