Abu Sa'id Taj ad-Dawla Tutush I (Turkish: I. Tutuş, Arabic: أبو سعيد تاج الدولة تتش السلجوقي) (died 1095) was the Seljuq emir of Damascus from 1078 to 1092, and Seljuq sultan of Damascus from 1092 to 1094.
In 1078, his brother Malik Shah I sent him to Damascus to help Atsiz ibn Uvaq al-Khwarazmi, who was besieged. After the siege had ended, Tutush had Atsiz executed and installed himself in Damascus.
Tutush finished the construction of the Citadel of Damascus, a project begun under the direction of Atsiz. Tutush took control of Syria in 1092, following the death of his brother, Malik Shah I, naming himself Sultan. Tutush, along with his general the Kakuyid Ali ibn Faramurz, were shortly defeated in a battle near Ray in 1095, where he and Ali were killed. Tutush was decapitated and his head was displayed in Baghdad.
Tutush's younger son Duqaq then inherited Damascus, whilst Radwan received Aleppo, splitting their father's realm.