The Bars class were a group of submarines built for the Imperial Russian Navy during World War I.

[1] The design had numerous shortcomings, including a lack of internal bulkheads and a slow diving time.

Surviving boats were modernized after the Russian Civil War by installing bulkheads, new diesels, pumps and extra torpedo tubes (the external drop collars were removed).

In the 1915 ice-free season they targeted German warships but with little success, these being generally fast and well-protected.

With the onset of the Bolshevik Revolution and the start of the Russian Civil War the surviving units in the Baltic were taken over by the Soviets and saw some action against Allied Intervention forces; in 1919 Pantera sank the British destroyer Vittoria.

[1] With the end of the Civil War the surviving Bars-class vessels remained in service until the 1930s before being discarded.