Isaiah the Solitary, also known as Isaiah of Gaza, Isaias the Solitary, Abba Isaiah, or possibly also Isaiah of Scetis, was a Christian ascetic and monastic writer known from the Sayings of the Desert Fathers and various Palestinian Miaphysite sources. He is canonized as a saint by the Coptic Orthodox Church, with his feast day on the 11th day of the month Abib (Epip) in the Coptic calendar.