| Reginald I Grenier | |
|---|---|
 Seal of Reginald of Sidon. | |
| Lord of Sidon | |
| Reign | 1171–1202 |
| Successor | Balian |
| Born | 1130s |
| Died | 1202 |
| Spouse | Agnes of Courtenay Helvis of Ibelin |
| Issue | Agnes Fenie (Euphemia) Balian |
| House | Grenier |
| Father | Gerard of Sidon |
| Mother | Agnes of Bures |
| Religion | Roman Catholicism |
Reginald Grenier (1130s – 1202; also Reynald or Renaud) was lord of Sidon and an important noble in the late-12th century Kingdom of Jerusalem.