The Koopalings are the love children of Bowser and Peach, born during Bowser's many, many, many kidnappings of her royal highness. Due to Bowser raping the princess so many times, there are seven of them in total.
They frequently invade Mushroom Kingdom territory for their father, due to the fact Bowser is too lazy to get off his throne, leave his castle located in the dark depths of a boiling volcano in Dark Land, and actually do so himself for a change, often simply trying to kidnap the princess instead.
Unfortunately for them, Bowser Jr is his favorite child, so they are widely considered all around the Mushroom Kingdom to be unloved and neglected. Because of this, they are frequently each odds against at each other at which one of them gets to kill Mario, Luigi, Toad, Mama Luigi, Dr. Rabbit, Kenny McCormick, King Harkinian, Weegee, Gay Luigi, Wario, Waluigi, and Donkey Kong in order to make their father proud of them.
- Ludwig von Koopa: A Koopaling that loves torturing people with his lousy singing. He is an obvious ripoff of Ludwig von Beethoven. He is the eldest and third-largest of the Koopalings.
- Morton Koopa, Jr.: A ferocious talkative ogre of a Koopaling who is also black, causing several other Koopas to try to lynch him. Despite being such a muscular brute, he is in fact the second-oldest and largest of the Koopalings.
- Iggy Koopa: A skinny, tall Koopaling (apparently he doesn't eat much) that is as insane as the Joker and loves spanking his ass whenever he sees Mario. He is the third-oldest and most medium sized of the Koopalings.
- Wendy O. Koopa: A Koopaling that throws tantrums and kills many people whenever Bowser doesn't give her what she wants. For some reason, she is the only female Koopaling around. She also wears a bow to hide her baldness. She is the fourth-oldest and second-smallest of the Koopalings.
- Lemmy Koopa: A midget Koopaling that rides around on his ball due to him being too lazy to walk. He wants to be in the circus. Strangely enough, he is the third-youngest and smallest of the Koopalings.
- Roy Koopa: A Koopaling that beats his siblings nearly to death on a daily basis. He wears sunglasses simply to make himself look cool, and is bald as a boiled egg. He is the second youngest and second largest of the Koopalings.
- Larry Koopa: A Koopaling that spies on girls while they're in the shower or changing clothes. He is the youngest and third-smallest of the Koopalings. For some reason he sometimes has a tendency to get lazy and save himself for last whenever the Marios go after him and his siblings.
- Koopa Troopa: It is not known if he his related to the Koopa's or not. He must be since his first name is Koopa, right?
Along with Bowser Jr, they once hid themselves inside a birthday cake and ruined Princess Peach's birthday party, kidnapping her in the process. Of course, Mario and Luigi (along with two random Toads) ultimately rescued her.
They once took over six of Bowser's seven Koopa hotels (Iggy did not get one because he had been bad). Mario and Luigi naturally invaded and kicked them out of them.
They once actually succeeded in kidnapping Mario (Morton and Lemmy did not get to participate because they had been stupid) and tortured him for days before he was finally rescued by Luigi.
They once turned a bunch of random kings nobody cared about in random animals, forcing Mario to try to change them back.
They once helped Bowser kidnap Peach and took over several lands. Since Larry was lazy, he stayed close to his father the entire time. Eventually, Mario killed every last one of them, but of course they came back to life.
They once assisted Bowser (who had been possessed by a girl) in destroying Mario and Luigi from within his own castle. All of them ended up getting pwned in rapid succession.