The X-Men in every incarnation displays this trope. X-Men being what they are, this is liable to fall under Bullying a Dragon.
This plays into a notable event in Rorschach's past in Watchmen. Rorschach was the son of a prostitute who often beat him. One day, when he was ten years old and sent out to get some milk, two fifteen-year-old boys accosted him and kept up the taunt of "whoreson" and demanded to be hooked up with Rorschach's mother. Rorschach, at age ten, partially blinded one boy with the boy's own cigarette, and swarmed the other one. Rorschach was taken into custody, and then put in state school when his home life was discovered.
Wiccan's backstory is this mixed with Beware the Quiet Ones; when a bully was beating him up for intervening, he accidentally electrocuted the boy, discovering his powers for the first time.
In the Calvin And Hobbes Tenth Anniversary Collection, Watterson muses a bit on the character of Moe, who was written as a bully from a child's perspective; which is to say that being a jerk is Moe's only purpose.
Moe is, in fact, the only recurring character in the entire strip not intended to be treated with any sympathy whatsoever.
The way Charlie Brown is treated in Peanuts, most of the kids could count for this (except Linus and Marcie most of the time)
The Plutonian, from Irredeemable, was forced to put up with bullying, as a child, because any retaliation could have killed the kids bullying him. After his Face-Heel Turn, he uses that to justify his willingness to murder children.