| Guillac | |
| Native Name: | Gilieg |
| Commune Status: | Commune |
| Insee: | 56079 |
| Postal Code: | 56800 |
| Arrondissement: | Pontivy |
| Canton: | Ploërmel |
| Mayor: | Stéphane Rouault[1] |
| Term: | 2020–2026 |
| Intercommunality: | Ploërmel Communauté |
| Elevation Min M: | 19 |
| Elevation Max M: | 91 |
| Area Km2: | 21.83 |
Guillac (pronounced as /fr/;) is a commune in the Morbihan department of Brittany in north-western France.[2] Inhabitants of Guillac are called Guillacois.