Boohemoth

"...a giant boo who is formed from the Matrix of Fear..."

Boohemoth is the largest subspecies of the Boos. It's one of the few invincible enemies in the entire Mario franchise, only defeated when the players reach the end of a level.

History
Boohemoth's only major appearance in Mario series has been in New Super Mario Bros. 2, only limited to 2 ghost house stages in the entire game.

In Prismverse Saga
In Prismverse Saga, Boohemoth's role is mainly limited as a mini-boss, only appearing in ghost houses/graveyard levels. His behaviour is mainly accurate to his NSMB2 counterpart, and defeated the same way: When the player reaches a certain point where the giant boo vanishes.

In Super Mario and the Star Prisms, Boohemoth only appears twice, as a mini-boss: In Gloomy Boneyard and Haunting Reverie Mansion.

Its appearances in future episodes is unknown.

Trivia

 * The music that plays during Boohemoth chases in SMATSP is a remix of Boss Battle theme from Super Mario Land 3: Wario Land, composed by the artist MODIGS.
 * This music is shared by a majority of the mini-bosses in the episode.

Lore
Boohemoth... The largest of its brethren. It's rumored to be born from pure phantom essence and from the embodiments of fear matrix, just like other various phantoms that lurk in certain places. But this one... is special. Meanwhile where most boos will never move unless one faces against their side, this one chooses to follow its victims, no matter what. But it doesn't appear everywhere. There are energy seals that keep them limited at certain locations, to limit their full powers. If one manages to free itself from these seals, their power will increase and increase until they become nigh-unstoppable.

One should never free a Boohemoth from its seals at any costs, dire consequences await to those who do so...