"Hiya, chumps! My papa was so mad when you took that GRAND STAR from him! Well, it won't happen this time! I'm gonna use this to power up the Mega-leg! You won't stand a chance! Oh, and don't worry about that kid... He's gonna die! Wahahahaha!"
— Bowser Jr., before activating Mega-leg in his first appearance

Bowser Jr. is an antagonist introduced in The Room of Super Mario Galaxy. He's the son of Bowser, and wishes to be as great as he is one day. Because of this, he constantly tries to stop the gang with his machinery. He is owned by Moon Snail, but is free-use in Mario-based rooms.


Before the gang appeared, he and his father teamed up constantly to kidnap Princess Peach. Once the gang appeared at their room, the two took the entire Mushroom Kingdom, as well as kidnap Lucas on the order of Necrola. Bowser Jr. stayed absent for a while, until the gang got to his own galaxy, Bowser Jr.'s Robot Reactor. He introduced himself to the gang, and awoke Mega-leg to take on the gang. After seeing it get destroyed, he apologized to his father, who was accepting of it. The two continued to stay and plan, especially to stop Lucas whenever he tries to escape. Eventually, he decided to help Necrola create a machine used to kill prisoners and turn them into Killer Robots. After finishing the machine, he heard the Mysterious Figure and a newly-introduced Thyme Warp named Espio making noise. He jumped into his Clown Car and took on the figure. Both of them dodged constantly, but when hit by one of his own Mechakoopas, he called his father over to stop him. The battle ended with neither side winning, as Jr. ran away and the figure disappeared into the shadows. After continuous spying by Lucas and Espio, he and Necrola caught Lucas and turned him into ARCHER. In Bowser's Galaxy Reactor, he appeared with Necrola on an airship to fire fireballs at the gang. He was barraged with attacks, so he ended up leaving.

Abilities and Weapons

  • Clown Car: He has a personal vehicle that can do the following:
    • Cannonball: It can shoot a cannonball.
    • Mechakoopa: It can shoot small robots that explode on contact. It is risky, however, as they can be stomped on and thrown back at him.
  • Fire Breath:Like his father, he can breathe fire.


  • Bowser: His father and most respected person. Most of his deeds were done in an attempt to live up to him. Bowser respects him as his son as well.
  • Mario: Bowser Jr. is, just like with Bowser, his greatest enemy. Many of his father's plans are foiled by the plumber, and despite his attempts to stop him, he usually fails.
  • Lucas: Bowser Jr. has a particular grudge with Lucas, thanks to the events of The Room of Super Mario Galaxy. He desires to capture him as much as he desires to capture Princess Peach, which can sometimes mess with his father's plans.

Villainous Acts

  • Sent Mega-leg to attack the gang.
  • Helped Necrola create her machine
  • Fought the Mysterious Figure with intent to turn him into a Killer Robot
  • Made a machine to create Prankster Comets, and then sending a comet to Beach Bowl Galaxy.
  • Helped Necrola kill Lucas
  • Disguised as Jelo Elducal in an attempt to get him jailed


  • Despite being young, he is shown to be very good at building machinery, such as Mega-leg.
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