Kets are a Yeniseian-speaking people in Siberia. During the Russian Empire, they were known as Ostyaks, without differentiating them from several other Siberian people. Later, they became known as Yenisei Ostyaks because they lived in the middle and lower basin of the Yenisei River in the Krasnoyarsk Krai district of Russia. The modern Kets lived along the eastern middle stretch of the river before being assimilated politically into Russia between the 17th and 19th centuries. According to the 2010 census, there were 1,220 Kets in Russia. According to the 2021 census, this number had declined to 1,088.

The Yenisey, also romanised as Yenisei or Jenisej, is the fifth-longest river system in the world, and the largest to drain into the Arctic Ocean.