The Oskil Reservoir (Ukrainian: Оскільське водосховище; Russian: Оскольское водохранилище, sometimes translated as Oskol, Oskilske -) was an artificial lake on the Oskil River in Kharkiv Oblast, Ukraine.

Before it was drained, the reservoir's area was 130 km², with a maximal length of 125 km, a maximal width of 4 km, an average depth of 4 m and a volume of approximately 474 hm³.

The purpose of the reservoir was to regulate water levels, to serve as a source for electricity, and to help the fishing industry.

[2] In July 2022, Russian shelling destroyed the reservoir's Oskil Dam, draining its level to one-sixth that of its pre-war size.

[3] The loss of water from the reservoir caused significant environmental damage, including the deaths of millions of fish and other endangered species.