The head of Russia's GRU military intelligence agency, Igor Korobov, has died aged 62, the defence ministry said on Thursday.
His successor has yet to be announced.
Korobov's predecessor, Igor Sergun, died in January 2016.
In recent years the GRU has gained notoriety over links to some of Russia's most contentious actions abroad.
The West has accused the powerful agency of a number of attacks on foreign soil including the poisoning of former Russian spy Sergei Skripal and his daughter Yulia, with a nerve agent in Britain last March.
The GRU is one of Moscow's three spy agencies along with the FSB security service and the SVR foreign intelligence agency.
(With inputs from agencies.)