One of Marvel's beloved superheroes, Spider-Man, introduced one of the most important maxims for superheroes - with great power comes great responsibility.
If superheroes did not use powers responsibly, they would be bullies at best and villains at worst.
We expect superheroes to use powers to defend the weak, but some superheroes, including the Avengers, are killers.
Here are five Avengers who have killed.
Beware the Widow's bite
Like the spider, she derives her name from, Natasha Romanova is adept at killing.
It is unsurprising that this Avenger is a killer considering her former training as a Soviet spy.
Black Widow in the movies is much more restrained, despite 'Avengers' movie alluding to her violent past.
Notably, Jasper Sitwell, who appeared in Winter Soldier, was killed by Black Widow in the comics.
The Avenger who caused a galactic genocide
Peter Quill or Star-Lord is actually a member of the Guardians of the Galaxy but they joined forces with the Avengers in 'Infinity War'.
However, before his heroic days, Quill was a Ravager working with Yondu and a member of the Shi'ar Imperial Guard.
Convicted of galactic level genocide and responsible for over 3,50,000 deaths, it is hard to comprehend Quill's heroism.
Whispered tales of gore
Thor or the God of Thunder is much more powerful in comics than the film.
He is also more aggressive and violent. Thor will kill if he deems it necessary to preserve life and has exterminated powerful evil with extreme prejudice, including Ragnarok, Malekith and Skurge the Executioner.
In comics, he even killed Loki once, for which he was banished from Asgard.
Step into the gory spotlight
T'Challa wears the mantle of the Black Panther in the comics and is the king of Wakanda.
As a king, his character is just, but he is willing to kill to defend and protect his people.
In Black Panther's defense, he has never killed civilians. However, in comics, when his wife Storm was kidnapped by the Skrulls, T'Challa decapitated a Super Skrull in retaliation.
One man Nazi killing machine
One would hardly expect Steve Rogers or Captain America to be a killer. He does not even allow indecent language in the Avengers!
However during his Timely Comics run, when he was just a super soldier before he became Captain America, he killed or tried to kill every Nazi he came across.
He gave up his firearm for his shield much later in comics.