Diyadin (Kurdish: Giyadîn; Armenian: Տատէոն, romanized: Tatēon) is a town in Ağrı Province of Turkey, at the foot of Mount Tendürek, a high peak in the Aladağlar range that stands between Ağrı and the north shore of Lake Van. It is the seat of Diyadin District. Its population is 20,302 (2021).