Apparently, Hollywood is filled with missed opportunities. Specifically, missed opportunities for killing your enemy (cue dramatic music).
An incredibly comprehensive supercut put together by Jukka-Pekka Bohm shows just how many times Hollywood has used the phrase, "I should have killed you when I had the chance," as well as iterations of said phrase. Spoiler alert: It's a lot.
The list of films included in this supercut is ridiculously long. However, as one commenter points out, "It's a pity Bilbo didn't kill him when he had the chance" from LOTR is missing. Come on. That's a great one!
Still, the guy did a bang-up job. Just check out the list of included films, including relative timestamps:
The Frozen Ground
Drop Dead Gorgeous
This Means War
Game of Death
Born to Be Bad