Cubitus emerges from the Belgian comic series crafted by draftsman Luc Dupanloup (Dupa), debuting in 1968. He appears as a large, fluffy white dog boasting a round physique, upright gait, and signature features: a thick black bulbous nose and a thick yellow fluffy tail. Anatomically, his name references the cubitus bone (elbow), linking thematically to bones, which correspond to his favored food, marrowbones.

Highly domesticated, Cubitus consistently displays an aversion to baths. His personality balances intelligence with extreme laziness, frequently devoting days to eating and sleeping. Despite this lethargy, he proves adaptable, stepping into roles like detectives or fairy tale characters when necessary. Cubitus resides with an inventive owner, identified across adaptations as Professor Dinghy, Semaphore, or Bojenberg. This owner devises quirky, frequently malfunctioning inventions that Cubitus often tests or suffers consequences from, though Cubitus himself demonstrates superior skill in meal preparation.

A recurring rivalry pits him against a cultivated black cat named Paustian (or Sénéchal), frequently targeted by Cubitus' pranks or antagonism. This dynamic fuels comedic clashes throughout the narrative. In the anime adaptation, Cubitus encounters additional neighborhood figures: Beatrice, a bossy woman harboring implied romantic interest in his owner, and Linda Lovely, a teenager showing fondness for him. His daily life typically involves navigating disruptions caused by the rival cat or the inventor's failed experiments.

His portrayal remains consistent across media, with no significant evolution in background or personality documented in available sources. Cubitus has been celebrated by cultural tributes, including a Brussels wall painting depicting him in a Manneken Pis pose and a 2002 statue in Limal, Wallonia, honoring both the character and his creator.