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
No Way Out
Bend of the River
The Dead Pool
Shriek If You Know What I Did Last Friday the Thirteenth