Kill the Ones You Love

Sometimes, a character you care for is going to die. Rather than killed off by the bad guys, the murderer is another character who cares very much for the deceased.

In any case, the characters know each other as well as their relationship to each other and the killer knows that the other has to die for anything to be resolved.

In video games, this is invariably a Player Punch. This trope usually doesn't villainize the killer since the now-dead character generally has to be killed to right wrongs or at least keep the story going.

This trope is only for the heroes/heroines have no choice, but to kill someone they loved like if they become a zombie or have turned into monster.

Examples

 * Subverted in the ending of Pan's Labyrinth, when Ofelia has to kill her baby brother to prove herself as a princess of another world. She refuses to do so. Soon, she's killed... and then she's spirited away to her real home anyway.
 * Kill Bill: At first, all we see of The Bride is her revenge against Bill, her ex-lover, but after she kills him, she breaks down sobbing for several moments.
 * Shaun of the Dead: Shaun shoots the zombie Barbara after her transformation.
 * X-Men: The Last Stand:
 * Jean Grey as the Phoenix kills both Professor X and Scott Summers.
 * Wolverine is forced to kill Jean to stop her murderous Phoenix alter-ego from destroying everything.
 * As mentioned in the Literature section, Old Yeller is one of the oldest examples in film. At first there is a Hope Spot tease when Travis pens the dog in a corncrib, hoping he won't turn rabid — he does.
 * Will Smith's dog in I Am Legend.
 * Veronica have no choice, but to shoot her former lover Seth who have been turned into a Brundlefly.