Ovid Densusianu (Romanian pronunciation: [oˈvid densuʃiˈanu]; also known under his pen name Ervin; 29 December 1873, Făgăraș – 9 June 1938, Bucharest) was a Romanian poet, philologist, linguist, folklorist, literary historian and critic, chief of a poetry school, university professor and journalist. He is known for introducing new trends of European modernism into Romanian literature.

The son of Aron Densușianu, a university professor at the University of Iași, and Elena (b. Circa), he received a degree from the Faculty of Letters, University of Iași, in 1892. Between 1893 and 1895, he studied in Berlin, Germany, and Paris, France. After he received his diploma from the École pratique des hautes études, Paris, in 1896, he worked his way up at the University of Bucharest, eventually becoming a professor in 1901. In 1918, he became a full member of the Romanian Academy.

Densusianu was briefly married to Elena Bacaloglu, who later came to admire fascism and organized the National Italo-Romanian Cultural and Economic Movement. He is buried at Bellu Cemetery, in Bucharest.

Streets in Călan, Hațeg, Oradea, and Pitești are named after him. A county library in Deva and schools in Călan, Făgăraș, and Hațeg also bear his name.