| Marseillan | |
| Commune Status: | Commune |
| Arrondissement: | Mirande |
| Canton: | Mirande-Astarac |
| Insee: | 32238 |
| Postal Code: | 32170 |
| Mayor: | Michel Raffin[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Cœur d'Astarac en Gascogne |
| Coordinates: | 43.4894°N 0.3175°W |
| Elevation M: | 225 |
| Elevation Min M: | 179 |
| Elevation Max M: | 273 |
| Area Km2: | 4.34 |
Marseillan (in French pronounced as /maʁsɛjɑ̃/; Occitan (post 1500);: Marcelhan) is a commune in the Gers department in southwestern France.