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StarTropes
Since: May, 2014
This is when the villian is captured or weakened and the side characters beg the hero to kill the villain.
Happened in One-Punch Man Webcomic
https://services.f-ck.me/v1/image/aHR0cHM6Ly9jZG4uZGlzY29yZGFwcC5jb20vYXR0YWNobWVudHMlMkY5MTcyMzEwMjc1Njk3MDA5MTQlMkY5MTcyNjcxMDIyMTYzNjQwNDIlMkYwMjMucG5n
And in the Invincible #60, where his brother begged to kill a villain too.
The hero usually either refuses to do so or really thinks about it.