Let Them Die

"Kirk: Don't believe them! Don't trust them!

Spock: They're dying.

Kirk: Let them die!"

Sometimes even the Hero gets utterly frustrated by a particular race or person, to the point that the race or person may face a horrible extinction or other horrible fate, and the Hero is just too jaded or disillusioned to care, usually by having been personally wronged by the race/person in question to a horrible extent, most often involving family or a friend having been killed by said race or individual's actions. Sometimes it is accompanied by a speech, sometimes it is just those three small, but powerful and life-changing (or life-ending) words. This trope often results in a What the Hell, Hero? moment, or at the very least a long, often loud objective lecture.

This trope is USUALLY applied to the Hero, but not always. However, the ones delivered by the hero are almost always the ones that get the most fervent objections from friends, or sometimes even change who was perceived as the hero into an Anti-Hero at best, or the Big Bad at worst.

Comic Books

 * Green Lantern Sodom Yat hated the xenophobia of his homeworld Daxam. It reached a peak in his childhood when he befriended an alien named Tessog that had crashlanded on Daxam. Sodom's parents brainwashed Sodom and murdered Tessog. Sodom realized the truth after seeing his friend's stuffed corpse in a museum. He repaired his friend's ship vowing to leave the planet forever when the Green Lantern ring appeared and gave him another out. Years later, when the Sinestro Corp attacked Daxam, Sodom seriously considered leaving the planet to its fate.

Film

 * The Trope Namer is Star Trek VI. Kirk is infuriated to find he has been nominated to extend "the first olive branch" of peace to the Klingons, who can no longer afford to maintain hostilities with the Federation. Kirk has hated the Klingons outright ever since they killed his son and when Spock attempts to persuade him that it's the right thing to do he names the trope.
 * Incidentally, originally Kirk was supposed to immediately recoil in shock at his own bloodthirsty outburst before amending "I didn't mean that", but it was cut. Apparently William Shatner was quite annoyed at the ommission.

Literature

 * In A Song of Ice and Fire many people counsel the Lord Commander of the Night's Watch to abandon the wildlings behind the Wall to be killed by the Others, due to the difficulty of saving them and their historical status as enemies of the Night's Watch. During one attempt to convince them why this is not a good idea, he points out that the Others raise the dead, and they're proposing giving their enemy thousands of soldiers.

Live Action TV

 * "And yet somehow, I just can't seem to care."
 * Doubles as an Ironic Echo since the villain pleading for help said the exact same thing when asked about all of the suffering he and his compatriots cause on a daily basis.

Video Games

 * For most of Mass Effect the Council has mocked you, questioned you, and otherwise screwed you, . At the climax, you have the option to  The dialogue tree option literally says, "Let the Council die!" Later, a renegade Shepard has the option to claim he/she was waiting for a chance to get rid of them all along, prompting a shocked response from Anderson and a smug response from Udina.
 * For a more individual-oriented example, in Mass Effect 2 on  loyalty mission you have to option to leave   to be presumably maimed and killed by his feral crew. Why? He set his mechs on you and his crew, brainwashed several of them to be mindless guards, forced most of the crew to worship him like a god, and  . His abuses are so unacceptable

Web Comics

 * In the webcomic Inverloch, the main character Acheron delivers this in reference to the Elves, justified because after a long, grueling, life-threatening journey to return a pendant and find a lost elf child, he finds out that  He gets some sense slapped into him by the group's token Elf chick (complete with ridiculously impractical clothes for fighting), who gives him a short What the Hell, Hero? which he responds pretty well to, even though it seems that he'd pretty much be justified in letting them go to hell, what with several broken deals that they made not only with his people, but with human mages as well,

Western Animation
"Superman: Good."
 * In the Justice League episode "Twilight", Darkseid shows up in the Watchtower and asks for the League's help since Brainiac is attacking Apokolips. Superman's response?