Konstantin Aleksandrovich Umansky (Russian: Kонстантин Aлександрович Уманский; 14 May 1902 – 25 January 1945)[1][2] was a Soviet diplomat, editor, journalist and artist.

[3] Umansky, whose family were of Jewish origin,[4][5] was born in Mykolaiv; he began studies at Moscow University in 1918, and joined the Russian Communist Party (Bolsheviks) in 1919.

[1] Later that year he moved to Germany where he soon started writing material informing the avant-garde art scene in Berlin of the artistic developments in Russia.

[6] In November 1920 he contributed a slide-illustrated lecture to a "Russian Evening" sponsored by the art magazine MA, produced by revolutionary exiles from Hungary who had fled there following the crushing of the Hungarian Soviet Republic.

Eugene Lyons, the correspondent of United Press recalled: Our conversation was on a high level of international affairs, but under it I read in his gold smile, "You dislike me because I'm an egocentric Soviet go-getter, but watch me rise to commissar..." In this suavely scheming Comrade Umansky, clever with the devious shrewdness of a clothing salesman, ironical to underlings and toadying to higher-ups, discreetly indulging a sybaritic streak, I was coming to see (Perhaps unfairly, but despite myself) the quintessence of revolutionary technique.

On 11 May 1939, Umansky was appointed by Joseph Stalin as Ambassador of the Soviet Union to the United States and he presented his Letters of Credence to U.S. President Franklin D. Roosevelt on 6 June 1939,[1] becoming, at the time, the youngest Ambassador in Washington, D.C.[9] In April 1941, Hans Thomsen, a diplomat at the German embassy in Washington, D.C., sent a message to Joachim von Ribbentrop, the German foreign minister, informing him that "an absolutely reliable source" had told Thomsen that the Americans had broken the Japanese diplomatic cipher (U.S. codename "Purple").

The historian Ian Kershaw wrote "When the unpalatable Soviet ambassador, Konstantin Oumansky, proved stubborn, unaccommodating and unwilling to acknowledge that gold reserves could be used to cover payments, an angry and frustrated Roosevelt described him in a Cabinet meeting as ‘a dirty little liar’ ".