| Lalleu | |
| Native Name: | (Gallo) |
| Commune Status: | Commune |
| Coordinates: | 47.8561°N -1.5089°W |
| Insee: | 35140 |
| Postal Code: | 35320 |
| Arrondissement: | Redon |
| Canton: | Bain-de-Bretagne |
| Mayor: | Thierry Lassalle[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Bretagne Porte de Loire |
| Elevation Min M: | 31 |
| Elevation Max M: | 104 |
| Area Km2: | 15.47 |
Lalleu (pronounced as /fr/; Gallo: Laloe, br|An Alloz) is a commune in the Ille-et-Vilaine department in Brittany in northwestern France.
The stream de la Couyère forms all of the commune's eastern border, then flows into the Semnon, which forms all of its southern border.
Inhabitants of Lalleu are called Allodiens in French.