| Honorific Prefix: | Saint |
| Adelin of Séez | |
| Birth Date: | unknown |
| Death Date: | c. 910 |
| Feast Day: | 10 November |
| Venerated In: | Roman Catholic Church Eastern Orthodox Church Anglican Communion |
| Titles: | Monk, Abbot and Bishop |
Adelin of Séez (also, Hadelin, Adelheim, Adelhelm, or Adalhelmus) (died c. 910) was a Benedictine monk and abbot at the abbey of Anisole.[1] He was the Bishop of Séez for twenty-six years starting around 884.[2] He is noted for authoring a work on the life and miracles of Opportuna of Montreuil (Vita et miracula Sanctae Opportunae).[3]