Dennis is a given name that can refer to:
- Dennis, a member of Dudley Dursley's gang
- Dennis Aldermaston, a Ravenclaw student at Hogwarts in the 1990s
- Dennis Bishop, a child who lived at Wool's Orphanage
- Dennis Creevey, a Gryffindor student at Hogwarts in the 1990s and younger brother to Colin Creevey