Gang rape is frequently touted as amongst the worst example, sometimes quite frivolously. I want to respond to this from the perspective of one who knows, because I was a victim of gang rape. I was also raped by one man in a separate incident, which I've only recognised in very recent years was actually also rape. I was fifteen on both occasions. I've spoken about this situation on MN before, largely because I don't believe silence in the face of this kind of crime benefits anyone other than the perpetrators.
It was a long time ago. The rapists got off scot-free, as so many rapists do. Their act messed with my head for many years. Do I actively wish them harm? No: time has enacted its own revenge. I've built a fantastic life for myself, largely on the back of an education I was capable of benefitting from as they were not. They are still the same pathetic losers they always were. (I knew all three of my rapists).
My father was a violent, alcoholic abuser who gave me concussion when I was in my mid-teens by slamming my head down a door. I ended with cPTSD. I did wish him harm, but only to the extent that I hoped he'd end up a sad, lonely old man. He didn't reach old age, but did experience a few years' loneliness before he left this planet.
Other than that, I didn't actively wish him harm but didn't shed a single tear when he died, either.
It's a trite cliche that the best revenge is to live well, and it really is. Another cliche - but cliches become cliches largely because they're true - is the one about drinking poison in the hope that someone else will die.
No one gets very long on this planet in the scheme of things. I refuse to waste my life in fantasies of revenge. That's giving others a power over me they simply don't merit.