Tosya is a town located in the Kastamonu Province within the Black Sea region of Turkey. It serves as the administrative seat of the Tosya District and has a recorded population of 28,963 as of 2021.
Historically known by the names Theodosia or Doceia during the Byzantine Empire, the town is recognized as the birthplace of Markos Vafeiadis, a prominent Greek politician who lived from 1906 to 1992. It is also noted as the hometown of the Boyner family.