The subject of Everything Burns by Anastacia & Ben Moody. The song could probably describe ninety percent of the characters with this trope. Rule of thumb, if you can't use this song as the character's theme song, don't put them here.
Upon discovering that his sister has died before he could find her again, Moira's Elefseus finally snaps from a lifetime of trauma and goes on a Roaring Rampage of Revenge against everything that ever played a part in his suffering, up to and including fate itself.
The female protagonist of Carrie Underwood 's "Blown Away". She apparently has supernatural powers and uses them to create a destructive tornado to kill her father in his sleep who was described as a "mean old mister" that apparently killed her mother.
Many of The Megas' interpretation of the Robot Masters count, as they are given their own backstories and motivations for wanting to help Wily. However, Air Man in particular stands out. He laments that his power only causes him to push others away, and decides...
Air Man: If I can't walk among them, then I will walk the world alone.
Bubble Man as well, as he wants only to prove to his brothers and to himself that he's not as weak and useless as they all say he is.
Very special mention goes to Crash Man. He doesn't even want to help Wily. He wants to join Mega Man to save the world. Unfortunately, he can't break his programming to fight against Mega Man. Except for right at the end, when he's about to finish Mega off, when he manages to break his programming for a brief moment, which he uses to throw the fight and kill himself so that Mega can go on.
"It's Getting Dangerous" by Thin Lizzy. (Hasn't had destroyed the world yet, but it's probably on his agenda.)
The power's at his fingertips
Vengeance is on his lips
But the power he fought to control
Now has got him in its grips
"Iron Man" by Black Sabbath is about a person who travelled time to save the world but, upon returning, is turned to steel and rejected and ignored by everyone he saved, leading him to turn vengeful and start killing them.