Gregory Thaumaturgus or Gregory the Miracle-Worker, also known as Gregory of Neocaesarea, was a Christian bishop of the 3rd century. He has been canonized as a saint in the Catholic and Orthodox Churches.

Niksar, historically known as Neocaesarea (Νεοκαισάρεια), is a city in Tokat Province, Turkey. It is the seat of Niksar District. Its population is 37,017 (2022). It was settled by many empires. Niksar is known as "Çukurova of North-Anatolia" due to its production of many kinds of fruits and vegetables. On May 2, 2018, Niksar was included in the World Heritage tentative list.