Vlas Yakovlevich Chubar (Russian: Влас Яковлевич Чубарь, Ukrainian: Влас Якович Чубар; 22 February [O.S. 10 February] 1891 – 26 February 1939) was a Ukrainian Bolshevik revolutionary and a Soviet politician. Chubar was arrested during the Great Terror of 1937–1938 and executed early in 1939.

The top Communist Party official in Ukraine during the 1932–1933 famine, Chubar was posthumously held culpable for those events by a Ukrainian court in 2010.

Chubar was from an ethnic Ukrainian peasant family. He was born in Fedorіvka, Yekaterinoslav Governorate, Russian Empire (now in Polohy Raion, Zaporizhzhia Oblast, Ukraine). His parents were illiterate peasants who owned a small plot of land.

He was arrested and beaten by gendarmes for belonging to a revolutionary group when he was 13 years old. After leaving school, he worked as a roofer. Chubar became a Marxist revolutionary during the 1905 revolution and joined the Bolshevik faction of the Russian Social Democratic Labor Party in 1907. He was a senior figure in Vesenkha in Moscow, and the Urals, in 1918–20.

Chubar returned to Ukraine in 1920, where he held a succession of economic posts, including running the Don basin coal combine in 1922–23. He was a member of the Central Committee of the Communist Party of Ukraine in 1920–36, and of its Politburo. In 1922, Chubar was elected a member of the Central Committee of the Soviet Communist Party. On July 13, 1923, Chubar replaced Christian Rakovsky as Chairman of the Ukrainian Sovnarkom. The government headed by Vlas Chubar was approved by the Eighth (1924) and the Tenth (1927) All-Ukrainian congresses of Soviets.

In the early 1920s, Chubar tried to resist allowing Ukraine to be controlled from Moscow. In 1920, he objected to the appointment of a Russian, Vyacheslav Molotov, as secretary of the Ukrainian communist party, claiming that he knew very little about conditions in Ukraine. Molotov was recalled after a year. In 1925, he objected to the appointment of Lazar Kaganovich who, like Molotov, was a trusted ally of Joseph Stalin, as First Secretary of the Ukrainian party. When their relations reached the breaking point in 1928 Stalin recalled Kaganovich, whose replacement, Stanisław Kosior, was much more acceptable to Chubar and other Ukrainian leaders.

Chubar became a candidate (non-voting) member of the Central Committee's Politburo in November 1926 – the first, and for many years the only ethnic Ukrainian to reach this level. He supported Stalin in the struggle against Leon Trotsky in the 1920s and made an "ugly speech" attacking Trotsky and others at the Central Committee session in October 1927 which resolved to expel them from the communist party.

Chubar originally backed Stalin's decision to force peasant farmers to join collective farms. He was one of the speakers at a crucial session of the Central Committee in November 1929 who attacked Nikolai Bukharin and others who opposed forced collectivisation. In March 1930, he reported that 63 per cent of peasant households in Ukraine had been collectivised. On 1 February 1932, despite evidence that the policy was creating a catastrophic fall in agricultural output and mass starvation, Chubar and Kosior co-signed an order, “On Seed”, ordering regional, city and district party committees to deny any seed aid to Ukraine's collective farms. This was the first of three documents bearing this signature from which the Kyiv Court of Appeal reached its verdict that Chubar was complicit in genocide.