A Skeleton with grayish bones, he most often wears a dark-green suit upon a red shirt and a matching fedora.
He has a thin black mustache and eyebrows.
His eyes consist of empty black sockets with dark gray orbital bones.
Hueso is a stern, yet passionate businessman who values his restaurant highly, to the extent that he would rather suffer bodily injuries than have his place of business damaged.
Señor Hueso was formerly a resident of the mystical Hidden City located deep beneath New York City, but now lives and works secretly in the surface world. He runs a hidden Yōkai pizzeria called Run of the Mill Pizza. He speaks with a Spanish accent.
At some point in his youth, Hueso became involved in his brother Piel's piracy. This led to him becoming a wanted fugitive in the Hidden City.
Señor Hueso was first seen (timeline-wise) in "Minotaur Maze", wherein he serves as the doorman of the Maze of Death. He informs Leonardo about the "World's Greatest Pizza" that can only be obtained by solving the maze and getting their pictures on their wall of champions. The only rule is that the use of magical items is not allowed. In addition, he has a Minotaur who works as the assistant manager of the maze.
In "The Fast and the Furriest," the Mad Dogs arrive at Run of the Mill Pizza looking for the culprit who stole the Turtle Tank. When they start asking some of the patrons about it, Señor Hueso critiques their "bad cop" routine. When Mikey states that they are not actually the police, Señor Hueso has them thrown out.
- He can detach his limbs and use them as weapons.
- When angered, he can transform his ribs into large appendages which can seemingly squeeze or crush anyone who is caught in them.
- He has exhibited a moderate degree of skill at fencing.
- Hueso, Jr.: Hueso's son who, based on Leonardo's description, may be a student at "Bone College".
- Capitán Piel: Hueso's brother, who tricked him into committing a crime when he was a child, resulting in Hueso becoming a wanted criminal in the Hidden City. However, the two of them have since since reconciled.
Friends and allies
- Todd Capybara: Hueso refers to him as his favorite customer. However, their exact relationship is currently unknown.
- Mad Dogs: Hueso finds them annoying, but usually patiently tolerates them, at least in part because they are some of his pizzeria's most frequent customers. Their cooperation has increased over time, like in "You Got Served" when a desperate Hueso called the Mad Dogs and asked them to fill in as temporary cooks and waiters on a day when all his restaurant's regular employees refused to show up, and Leo and Mikey arrived to fill in. But Hueso also regards the Mad Dogs as an unreliable wild card who are prone to creating as much trouble as they can solve.
- Leonardo: Leo was the first of the Mad Dogs to meet Señor Hueso in "Minotaur Maze", and the one who has been most shown interacting with him since then. Leo has twice wrangled a reluctant Hueso into visits to the Hidden City. The first time, in "Portal Jacked!", Leo came to Hueso, who was one of the Mad Dogs' few regular Yōkai contacts, for information and help after Leo's brothers disappeared during one of their portal trips using Leo's mystic ōdachi. Hueso explained portal-jacking to Leo and showed him a nearby portal to the Hidden City, but Leo impulsively dragged Hueso along, not knowing Hueso was actually a wanted fugitive there. Hueso's unplanned outing and search for clues brought him and Leo into contact with Hueso's criminal estranged brother Capitán Piel, and ultimately not only reunited Leo with his missing brothers, but also proved Hueso's innocence of the crime he was wanted for. The second time, in "The Hidden City Job", Piel came to visit Hueso at the restaurant while Leo was trying to order a pizza for Donnie, and Piel asked Hueso for help in an ostensibly ethically-justifiable heist in the Hidden City. Hueso was distrustful of his brother and did not want to get involved, but Leo talked Hueso into helping and also tagged along. In the course of events, Leo was instrumental in helping Hueso reconcile with Piel. Also, when Hueso and Piel temporarily fused into the extremely handsome Don Suave, Leo (along with Big Mama) was intensely physically attracted to him.
- Michelangelo: Mikey, along with Leo, showed up at Hueso's request in "You Got Served" to fill in as temporary cooks and waiters.
- Big Mama: She and Hueso are not established enemies per se, but Hueso does not want anything to do with the notorious crime boss. When the already reluctant Hueso agreed to help his brother Capitán Piel, Piel had not told Hueso that the item he had planned to reclaim was located in Big Mama's auction house, knowing Hueso would never agree if he knew Big Mama was involved. After their ultimately successful heist, Hueso, Piel and their companion Leonardo escaped when Hueso and Piel fused into the extremely attractive Don Suave, whose sheer dashing good looks and personal charm not only completely dissolved Big Mama's hostility, but actually had the force of power to destroy the soldiers who had accompanied her.
- The name "Señor Hueso" is of Spanish origin, and translates to "Mister Bone" in English.
- In the series, Hueso's name is normally pronounced /ˈhwe.so/ HWAY-soh, with a non-silent H. But in the Spanish language, the word hueso is normally pronounced /ˈwe.so/ with a silent H. As such, the show pronounces Hueso's name as if its Spanish spelling were "jueso."
- He sometimes detaches his own left arm and uses it as a cane.
- Although he appeared first in "The Fast and the Furriest" and the Mad Dogs were already familiar with him, they didn't meet him until "Minotaur Maze." This suggests that the episodes were aired out of order.
- Eric Bauza voices Señor Hueso while doing an impersonation of Antonio Banderas.
- In "Portal Jacked!", some information about his family was revealed: