| Aignan | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Aignan (Gers).svg |
| Arrondissement: | Mirande |
| Canton: | Adour-Gersoise |
| Insee: | 32001 |
| Postal Code: | 32290 |
| Mayor: | Gérard Pérès[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Armagnac Adour |
| Coordinates: | 43.6986°N 0.0842°W |
| Elevation M: | 165 |
| Elevation Min M: | 107 |
| Elevation Max M: | 222 |
| Area Km2: | 32.16 |
Aignan (in French pronounced as /ɛɲɑ̃/; Occitan (post 1500);: label=[[Gascon language|Gascon]]|Anhan in Occitan (post 1500); pronounced as /aˈɲa/) is a commune located in the west of the Gers department in the region of Occitania. It is a rural community with 726 inhabitants as of 2019, down from a peak of 1,771 in 1831. The name Aignan comes from the Latin "Annius" followed by the suffix "anum", which likely refers to the region's owner during the period of Roman Gaul. The town was previously known as Aignan-la-Justice.
Aignan is located in the canton of Adour-Gersoise and in the arrondissement of Mirande.