In 'Notre-Dame de Paris' (1831) by Victor Hugo, Jehan Frollo "du Moulin" is Claude Frollo's 16-year-old dissolute younger brother. He is a troublemaker and a student at the university.
Jehan Prouvaire is one of the revolutionary students in Victor Hugo's Les Misérables. A different character also bears this name in Notre Dame de Paris.
https://en.wikipedia.org/wiki/Jehan_Alain
https://en.wikipedia.org/wiki/Jehan_Georges_Vibert
https://en.wikipedia.org/wiki/Jehan_Desanges