this is one of my least favorite tropes and it is especially ridiculous when the heroes have just shot their way through an army of mooks to get to the villain
oh, you can kill 475 henchmen but the guy who is actually responsible for ordering them around is a step too far? do you hear yourself?
Carrot would do it, Vimes would pause and listen because he fears that's true, Carrot wouldn't register that claim as sensible and stab them while they were talking and sadly comment it's tragic that it came to this
Feels like something The Punisher would do. Probably to some right wing tool talking about pizza-parlor-based child trafficking rings.
Or Deadpool, but the villain could be anyone at that point. Like Prof. X.
I honestly loved that in Dune Part 2 where Jessica said "Your father didn't believe in revenge" and Paul replied "Yeah, but I do"
...And shivs the Baron right under his jaw into his brain before having him dumped for the ants to eat. I mean, it's a heel turn for Paul but damn that was good.
Read a fun rebuttal to that, can't remember it fully but the point was that Hero IS different to Villain, cause Hero wouldn't be able to sleep at night after committing all those crimes, whereas Villain could, can and does. So Hero can kill Villain, do it.