Game: World of Warcraft
Killed by: Tirion Fordring
Video of death: YouTube

Before you jump to any conclusions about Arthas Menethil, consider the fact that Menethil is one of the more relatable villains you'll find in all of World of Warcraft. In the same way that Boromir was corrupted in Lord of the Rings, Arthas represents the folly of man, and how easily power can be corrupted. Because of this, we almost want him to survive just to serve as an example that redemption is possible in anyone. If the Lich King had been able to turn around his ways, then there would've been hope for us all.