Sergei Stanislavovich Yeliseyev (Russian: Сергей Станиславович Елисеев, Ukrainian: Сергій Станіславович Єлісєєв; born 24 October 1961[1]) is a Vice Admiral, former First Deputy Commander and acting commander-in-chief of the Ukrainian Navy who defected to Russia in 2014 during Russian annexation of Crimea.

[2] In 1993, Yeliseyev joined the newly formed Ukrainian Navy and in 1999–2001 he was a commander of Ropucha-class landing ship U402 Kostyantyn Olshanskyi.

[3] In 2010, he was appointed the First Deputy Commander of the Ukrainian Navy and later on promoted to Vice-admiral.

In March 2014, he broke the military oath of the Ukrainian Armed Forces and sided with the Russian Federation against Ukraine along with another high-ranking military officer, the appointed commander-in-chief of the Ukrainian Navy Denis Berezovsky in the wake of the annexation of Crimea.

In August 2014, the Military Prosecutor's Office of Ukraine accused Eliseev of treason and desertion.