St. Nicholas Cossack Cathedral, Orthodox cathedral in Omsk, Russia.

St. Nicholas Cossack Cathedral is a Russian Orthodox cathedral in central Omsk, Russia, with white walls, multiple gilded domes, and a tall bell tower that rises above the nearby buildings. The interior follows the standard layout of an Orthodox church, with an iconostasis separating the nave from the sanctuary.

The foundation stone was laid on 15 May 1833, funded by donations from Siberian Cossack troops and Omsk residents. The design is attributed to Vasily Stasov, with working drawings by Colonel A.A. Leshchev and provincial architect P.I. Praman. The main altar was consecrated on 16 September 1843. Closed by the Soviets in 1930, the building later housed a cinema and a concert hall before being returned to the Orthodox Church in 1998.

The cathedral kept the banner of Yermak Timofeyevich, the Cossack ataman who conquered Siberia, acquired in 1883; the original was lost in 1918 and a copy is kept today. The iconostasis was carved by a team under Vladimir Malykh to a design by Vasily Gulchenko, with gilding by Oleg Zotin. The church has three altars: Saint Nicholas, Simeon and Anna, and Saint George.

The cathedral is in the city center and easy to reach by public transport or on foot from the main streets. Visiting outside of service times gives more freedom to look around inside, and modest dress is expected when entering.

The cathedral is dedicated to Saint Nicholas, the patron of travelers and sailors in Orthodox tradition, a choice that carried real meaning for Cossack soldiers who spent much of their lives moving across vast territories. This dedication connects the building to the daily risks and journeys of the people who built it.