10 Worst Things Black Widow Has Ever Done
5. Killing Jarvis - Ultimates 2 #9
Be he a snarky butler or an elaborate A.I system, Jarvis is a beloved entity in most Marvel enterprises - which is why Black Widow established herself as a villain in the Ultimates series by planting a bullet straight into his skull, killing him instantly.
This would have been bad enough had she merely snuck into Tony Stark's mansion to murder the man, but it's actually far, far worse. As a spy, Natasha had snuck her way into Iron Man's affections, even agreeing to get engaged to the superhero. This is all a ploy to gain the Avengers' secret, however, and thus when Natasha decides it's time she left, she does so in usual dramatic fashion, stopping to kill Jarvis as he brings the couple their breakfast in bed.
Being evil is one thing, but shooting a man who's literally bringing you quail's eggs and a glass of OJ is definitely crossing the line.