Goomboss

Goomboss is the self-proclaimed king of the goombas and a high-ranking member of the Koopa Troop.

Early life
Goomboss was a regular goomba working under the Koopa Troop.

Paper Mario
When Bowser got ahold of the Star Rod in Paper Mario, he begged Bowser to make him a king. Bowser granted him his wish and, as a result of this newfound power, called himself the Goomba King.

Bowser then stationed the Goomba King, along with the Goomba Bros., inside a fortress that recently used to be a bridge between Goomba Village and Toad Town. There's a wireless switch that turns the fortress back into a bridge, which the Goomba King put Red Goomba on duty to hide.

Goomba King opened to gates of his fortress when the Goomba Bros. retreated inside after their defeat by Mario. When Mario and Goombario arrived in front of his fortress, the Goomba King proudly announced himself and that the two of them can't continue further. He jumps out of his fortress and attacks the duo, with aid from the Goomba Bros. Unfortunately, the fight does not go in his favor and he retreats back to his fortress.

After conversing with the Goomba Bros. and discovering that Red Goomba hid the switch inside the bushes outside, Goomba King attempts to trick Mario into believing that the switch is dangerous. However, by the time he wanted to tell Mario, he had already pressed it.

The process that turned the fortress back into a bridge launched the Goomba King to a far-off distance. He lands inside a tree unconscious, which then got used in the victory parade days after Bowser's defeat. He finally falls off its branches, waking him up and making him angry.

Super Mario 64
Now calling himself Goomboss, he was part of the invasion on Peach's Castle in Super Mario 64. Specifically, he was part of the group of bosses to ambush Mario, Luigi, and Wario in Bob-omb Battlefield and trap each of them inside the castle's rooms. Goomboss had the honor of holding the key that traps Mario and retreated inside Goomboss Battle.

Yoshi entered his arena and fought Goomboss for Mario's freedom, once again in disbelief he was beaten. He gives the key to Yoshi and explodes in anger.

Mario Kart DS
Goomboss raced against Toad in Baby Park during Mario Kart DS' Mission Mode. Throughout the race, he would try and pop Toad's three balloons by sending in his goombas and cheat by jumping over the course's center divider as a shortcut.

Personality
Goomboss is very prideful and confident in himself, calling himself "great and powerful". When Red and Blue Goomba egg him on to beat up Mario, Goomboss confidently believes he can defeat him on his own. He calls himself "no ordinary Goomba", "the great Goomba", "the grand pooh-bah Goomba".

He can't handle defeat. When anyone does defeat him, Goomboss can't believe what is happening and attempts to pull off an underhanded tactic, such as lying that the switch in the Goomba King Fortress is dangerous or jumping over the center divider in Baby Park. After being defeated by Yoshi, he repeatedly mutters that he can't believe he's been defeated, even making excuses in Luigi's case by stating that there must've been a mistake.

This defeat gives in to anger, this overblown anger often causing him to actually blow up.

Mario
He respects Mario for making it to his fortress. When he finds out the switch that turns his fortress into a bridge is outside, he believes Mario is smart enough to find it, but dumb enough to tell him it's dangerous to not press it. After locking Mario up in a room, he believes he's crying like a baby.

Yoshi
Goomboss first sees Yoshi as a prehistoric wimp. After being beaten by him, he still considers Yoshi a pip-squeak and can't believe he lost to him.

Luigi
Goomboss doesn't recognize Luigi, at first believing he's Mario due to the similar mustaches. He's especially confident in defeating Luigi, calling him a pip-squeak even after defeat, even believing his defeat against Luigi to be a mistake.

Wario
Goomboss at first did not pay mind to Wario and only fought him because he stomped on goombas once. After being defeated by Wario, Goomboss respects his abilities and mustache, promising to fight him again if only his own schedule wasn't packed.

Abilities
Goomboss makes use of his environment and size, such as by using his ground stomp to make a Goomnut land on Mario's head. In Super Mario 64 DS his method of attack is to charge straight at his foe. His actual attacks only extends to spin-kicking.

Since Super Mario 64, Goomboss gained the ability to grow in scale with his anger. This is dangerous, as growing too much causes him to implode on himself, which often happens because of his explosive anger. He can also summon goombas, either from the front or the back and in large numbers. This power of summoning also extends to Super Mushrooms