Olt may refer to:
- Olt County, a county (judeţ) of Romania
- Olt Defile, a defile that has been cut into the Transyvanian Alps in south-central Romania by the Olt River
- Olt River, a river in Romania
- Lot (river), a river in France
- Pârâul Olt, a tributary of the Pădureni River in Romania
- Károly Olt (1904–1985), Hungarian politician
- Optical line termination, a piece of telecommunications equipment used for fiber-optic communications