Entresol was the brutish, narrow-minded chief of staff of the Moustic Hotel in Brussels throughout the late 1930's and early 1940's. As such, the authoritative employee often antagonized mischievous bellhop Spirou, who paid back in kind with tricks galore.
Behind the scenes
M. Papillon debuted in the 1938 comic page Spirou n'aime pas l'eau — Spirou doesn't like water in English. Being a Spirou character, he does not belong to the Walt Disney Company, although Spirou is considered canon on this wiki.
In Émile Bravo's non-canonical prequel series Diary of a Naive Boy, Entresol's first name is established as Jean-Baptiste and he is shown dying in a bomb explosion during World War II. In the canonical universe, Entresol's fate (and first name) remain unknown.
"Entresol" is the French word for a mezzanine floor, making it rather an appropriate name for hotel staff.