I was reading and reviewing a few series on the weekend and in the process I came across a couple of great overkill moments, essentially that the character has already killed the enemy once over and then just decides to completely make sure that their adversary is dead. I should note that there are spoilers ahead (though it likely doesn't matter because who reads Dejah Thoris or Danger Girl?). The first of these was from the series Back in Black where Johnny Barracuda and Secret Agent Zero are sneaking around on a ship when they get discovered
The second is from the first story arc of Dejah Thoris, where she has been given a pair of wings for flight and a sword that can shoot one fairly powerful blast.
I might keep posting here as I come across these but feel free to share any others that you have come across.