Seversk is a closed city in Tomsk Oblast, Russia, located 15 kilometers (9.3 mi) northwest of Tomsk on the right bank of the Tom River. The population was 108,590 at the 2010 census and 109,106 at the 2002 census.

A closed city or town is a settlement where travel or residency restrictions are applied so that specific authorization is required to visit or remain overnight. Such places may be sensitive military establishments or secret research installations that require much more space or internal freedom than is available in a conventional military base. There may also be a wider variety of permanent residents, including close family members of workers or trusted traders who are not directly connected with clandestine purposes.