Goomboss

"Bwa ha ha! I'm no ordinary Goomba... I am Goomba king, the great Goomba, the grand poo-bah Goomba."

- Goomboss

Goomboss, also known as the Goomba King or Chestnut King, is one of the first bosses Mario and Goombario encounter in Paper Mario. He later reprises his role as a boss in the games Super Mario 64 DS and Mario Kart DS. It is noted that he is one of the only Paper Mario characters that returned in other Mario games.

Paper Mario
In Paper Mario, He is accompanied by Red Goomba and Blue Goomba. Mario will find him by his Fortress The easiest way of defeating him is to hit the Goomnut Tree to make Goomnuts fall on him, doing three damage. Originally, he was an ordinary little Goomba, but Bowser used the Star Rod to make him a king (which also greatly increased his size) under the conditions that he would assist Bowser later on.

After Mario defeats the Goomba King and his lieutenants, Red Goomba and Blue Goomba, Kammy Koopa is secretly observing the battle. She reports back to Bowser, who is furious at the defeat and also yells "I only used the Star Rod to make him to make a king because he begged me to!"

In the ending parade of Paper Mario, Red and Blue Goomba are trying to get the Goomba King out of a tree. He then falls out, and dizzily wobbles off the screen, followed by the Goomba Bros.

Paper Mario: The Thousand-Year Door
The unseen Chestnut King spoken of in Luigi's adventures has the same name as the Goomba King in Japanese (Kuri King), which would add more confusion since there are three English names inconsistently derived from it. As such, this is more than likely intended to be a reference to the same character. For more information on his backstory in that game, see the Chestnut King article.

Super Mario 64 DS
He also appeared in Super Mario 64 DS, now under the name of Goomboss (though still a king as indicated by his Japanese name, which would be a continuity error if this remake were considered canon). Yoshi had to defeat him by eating Goombas and spitting them back at him in order to win back Mario's key to use him in the game.

Mario Kart DS
In the missions section of Mario Kart DS, Toad must complete three laps of the Baby Park course before the Goomba king does. After each lap, Goomba king becomes bigger and bigger, but he has to stop for a few seconds to grow, giving Toad a chance to pass him. Another chance to pass him is when he stops to throw one Goomba on the first lap; one or three Goombas on the second lap; or one, three, or five Goombas on the third lap. If Toad hits a Goomba, he will lose one of his three balloons. If Toad loses all three balloons, he will fail the mission. Occasionally, Goomba king will throw a Mushroom instead of a Goomba, allowing Toad to get a boost of speed. Additionally, on the third lap, Goomba king will cheat and Jump over the center divider, improving his chances of winning. If Toad is in front of Goomba king, the Goomba King will not stop to toss Goombas but will run as fast as he can to catch up.

Trivia

 * Goomba king and the Star Spirits are the only characters that debuted in a Paper Mario series game to later reappear in a 3D game.