The Koopa Kids are minions of Bowser who have only appeared in the Mario Party series. They are known as Mini-Bowsers in PAL territories, Mini Koopa in Japan (Bowser's name in Japan is Koopa) and Baby Bowsers in Mario Party, Mario Party 2 and Mario Party 3. The Koopa Kids resemble miniature versions of Bowser (and are therefore very similar in appearance to Bowser Jr. and Baby Bowser). Originally, the Koopa Kids were nothing more than minions indirectly fought by the Mario crew when the Koopas attempted to crash their parties, but in Mario Party 5, one was finally made playable (despite this, Bowser shows them no mercy when they land on his space. This is obviously so players using Koopa Kid do not have an advantage).
It is unknown how many Koopa Kids there are. Originally, there seemed to be only a few, but Mario Party Advance implied there may be hundreds of them.
Mario Party 5 also introduced Green K. Kid, Red K. Kid and Blue K. Kid who, as their names imply, are colored differently. The aforementioned colored kids are one Koopa Kid split into three. It is unknown if other Koopa Kids are also capable of duplicating like this.
Koopa Kid's future is uncertain, as he did not appear in Mario Party 8, Mario Party DS, or Mario Party 9. Additionally, Bowser Jr. made his Mario Party debut in Mario Party DS and later again in Mario Party 9, implying that Koopa Kid may have been retired in favor of him.
 Mario Party
In Mario Party, a group of seven Koopa Kids appeared on the Eternal Star board, and each had to be dueled to win a Star by rolling a Dice Block for twenty Coins. The player had to roll a higher number, which usually happened, as their Dice Block was often rigged to ensure a high roll. Once all seven Koopa Kids were defeated, a new set appeared.
 Mario Party 2
In Mario Party 2, Koopa Kid appeared on every board. On most boards, he waited in one spot, much like Toad, and would steal five Coins from each player that passed him. On occasion, he would mess up and give a player five coins by mistake. Whenever Toad moved after selling a Star to someone, Koopa Kid would move to Toad's old spot. Koopa Kid also hosted Bowser Land, where he took over Toad's role as host. Here, he ran the Bowser Parade.
A particular Koopa Kid banker also ran the Bowser Bank. Unlike standard Koopa Kids, the Koopa Kid Banker had a blue head and wore glasses. Whenever a player passed by the Bank Space in Bowser Land, the Koopa Kid banker would give them a five coin loan, and would keep track of the total number of coins that he has loaned out to the four players. If someone ever landed directly on the Bank Space, they will be forced to pay back all of the coins that the Koopa Kid banker had loaned out at that point out of their own pocket. If the player did not have enough coins, the Koopa Kid banker would settle for all of them. If the player has no coins at all, the Koopa Kid Banker would take a Star from the player, provided they have one.
Additionally, a certain Koopa Kid shopkeeper ran an Item Shop in the Bowser Land, where players were forced into buying random items. The Koopa Kid shopkeeper had a red head and wore a monocle over his left eye. Whenever a player passed by his, the Koopa Kid shopkeeper would stop them in their tracks, and force them to buy a random item for a random amount of coins, usually between twelve and twenty. Each item the shopkeeper was selling cost more then when bought at a regular Item Shop. Players had no option but to buy the item. If they did not have enough coins, the Koopa Kid shopkeeper will take whatever they have, unless they are out of money.
 Mario Party 3
In Mario Party 3, Koopa Kid ran his own Item Shop, which sometimes appeared in place of Toad's, where he sold sneaky items such as Lucky Lamps, Reverse Mushrooms and Boo Bells. Koopa Kids also appeared in the Item Minigame, where they often symbolized losing, such as the Koopa Kid space in Winner's Wheel.
In Duel Mode, Koopa Kid also appears as one of the possible partners. He isn't a default partner, but can be obtained through the lottery. His attack is one, and his health is one. He can occasionally turn into Bowser and deal triple damage when attacking; however, if the transformation fails, he deals no damage. Koopa Kid's salary is three coins per turn.
 Mario Party 4
In Mario Party 4, a Koopa Kid would usually come in place of Bowser whenever someone landed on a Bowser Space, and would steal Coins from either the player who landed there, or from all the players. Sometimes, the Koopa Kid would then call Bowser after stealing coins, and a Bowser event would begin. In the Bowser Minigames, two Koopa Kids worked as Bowser's servants; one of which was seen fanning him and the other one explains the rules to the game (which may be Fruits of Doom, Darts of Doom or Balloon of Doom) and in addition, he also brings the dart board to the players and announce the scores in Darts of Doom. One also hosted the last board: Bowser's Gnarly Party and could be seen selling items and hosting board games. In addition, Koopa Kid can be unlocked in the volleyball minigame.
 Mario Party 5
In Mario Party 5, Koopa Kid was playable, but not in the Story Mode. In the Story Mode, Koopa Kid split up into Red K. Kid, Blue K. Kid and Green K. Kid, and the player had to steal all their coins on abridged versions of the regular boards to defeat them. In Card Party, Koopa Kid shows up to cause trouble on the Bowser Card. In the PAL version of Mario Party 5, they were called Mini Bowser, Red M. Bowser, Blue M. Bowser and Green M. Bowser.
 Mario Party 6
In Mario Party 6, Koopa Kid retained a role similar to that in 5, except that Red K. Kid, Blue K. Kid and Green K. Kid were the rivals in the Solo Mode, and the goal was not to defeat them. Rather, they just served as opponents during Minigames.
 Mario Party 7
In Mario Party 7, Koopa Kid was no longer playable. Instead, he appeared whenever someone landed on a Koopa Kid Space, and would do things such as swapping players' coins or positions, or use a Cursed Mushroom on the player/team who landed on his space. Red K. Kid, Blue K. Kid and Green K. Kid were also the main antagonists in the three multiplayer Bowser minigames, and operated the cannons in Bowser's Enchanted Inferno!.
 Mario Party Advance
In Mario Party Advance, Koopa Kids could be seen working with Bowser, and appeared in some of his minigames, where the object was usually for the player to defeat them. Up to ninety-nine of them could appear at once. One main Koopa Kid appears throughout the game as Bowser's right-hand man, often appearing to antagonize the player by doing things such as stealing Mushrooms from them or flinging them somewhere else on the Board Map.
 Relationships with Other Characters
In Mario Party 4, whenever a Koopa Kid called for Bowser, he would refer to him as "Dad". However, it is unlikely that Bowser is the biological father of all the Koopa Kids, and that the Koopa Kids may just be clones of some nature. Bowser's real son is most likely Bowser Jr. Similarly, Bowser also grounds them by taking away their Mario action figure if they fail him, hinting that Bowser at the very least has a father-like relationship with them. It's possible that Koopa Kid has a teacher-student relationship with Bowser since he calls him "Mr. Bowser". While the small Koopa shows a lot of loyalty to Bowser, he also takes the side of Mario and company every once in a while, as evidenced in Mario Parties 5 and 6. It is also likely that Koopa Kid works for Bowser for money, due to him telling himself, "I bet Mr. Bowser will totally give me a raise after this!"
 Character Artwork
 List of Appearances by Date