From the Super Mario Wiki
BISDX- Dieter Pose.png
First appearance Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey (2018)

Dieter is the leader of the Best Fitness Friends and a major antagonist in Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey. He is a tall figure wearing yellow and black clothing with a prominent tie, and takes charge of the group's operations. He uses various German terms, including telling Bowser Jr. "auf wiedersehen" (farewell) before trying to kill him. This is likely due to "Dieter" being a German name, while in English, it fits in with the food-based theme naming the other Best Fitness Friends have (in his case "diet", as in forsaking meals for the sake of losing weight). He is a ranged enemy in battle.

He is first battled in Bowser Path, where he and Kaley take on the Captains from Mario & Luigi: Superstar Saga + Bowser's Minions after knocking out Ludwig and Bowser Jr.

After this, he is next fought alongside the other two Best Fitness Friends members in the final battle, and merges with them to form the final boss before being defeated for good.


The brains of the BFF. He will achieve his goals by any means necessary.

Names in other languages[edit]

Language Name Meaning
Japanese スーリム