Otto Emil Franz Grotewohl (German pronunciation: [ˈɔtoː ˈɡʁoːtəvoːl]; 11 March 1894 – 21 September 1964) was a German politician who served as the first prime minister of the German Democratic Republic (East Germany) from its founding in October 1949 until his death in September 1964.

Grotewohl was a Social Democratic Party (SPD) politician in the Free State of Brunswick during the Weimar Republic and leader of the party branch in the Soviet Occupation Zone after World War II. Grotewohl led the SPD's merger with the Communist Party (KPD) to form the Socialist Unity Party of Germany (SED) in 1946 and served as co-chairman of the party with KPD leader Wilhelm Pieck until 1950. Grotewohl chaired the Council of Ministers after the formal establishment of the GDR in 1949 and served as the de jure head of government under First Secretary Walter Ulbricht until his death in 1964.

Grotewohl was born on 11 March 1894 in Braunschweig to a middle-class Protestant family, the son of a master tailor, and was apprenticed to a printer. At the age of 16 he joined the youth wing of the Social Democratic Party of Germany. Grotewohl served in the 137th Infantry Regiment [de] of the German Army during World War I (in which he was wounded several times), and served as chairman of the workers' and soldiers' council of the troops on the German-Dutch border from 1918 to 1919. He started his political career after the war as a leader of the Independent Social Democratic Party of Germany (USPD), and in 1920 was elected to the Landtag of the Free State of Brunswick in the Weimar Republic. Grotewohl served as a minister in numerous cabinets of the Brunswick state government, including Minister of Justice and Education from March to May 1922, and Minister of Justice from February 1923.

In 1922, Grotewohl and the majority of the USPD members joined the Social Democratic Party, and on 31 October 1925 he became a member of parliament in the national Reichstag to replace the SPD representative Elise Bartels after her death. Grotewohl was elected to the Reichstag in his own right in the September 1930 election and re-elected in the July 1932, November 1932, and March 1933 elections.

Grotewohl was eventually dismissed as a representative in the Reichstag after the Machtergreifung, the establishment of Nazi Germany, and like other SPD members was subject to discrimination. On 23 March 1933, Grotewohl had voted against Chancellor Adolf Hitler's Enabling Act, a constitutional amendment allowing Hitler to enact laws without the Reichstag's approval, which passed. Grotewohl was brutally beaten, arrested and imprisoned several times by Nazi police and subsequently forced to leave Braunschweig, first moving to Hamburg then from 1938 to Berlin, where he worked as a greengrocer and industrial representative. Grotewohl joined a resistance group centered around Erich Gniffke, an SPD politician he knew from Braunschweig, but the group ended up ensuring the contact and economic survival of its members rather than resisting Nazi rule. In August 1938, Grotewohl was again brutally beaten, arrested and charged by Nazi police with treason before the People's Court. On 4 March 1939, Grotewohl was released from pre-trial detention and the court's procedure against him was discontinued after seven months. Grotewohl was again brutally beaten and arrested by Nazi police after Georg Elser's attempted assassination of Adolf Hitler and other high-ranking Nazis on 8 November 1939, spending about eight weeks in custody before being released. Grotewohl worked as a clerk in Berlin after his release and increasingly devoted his time to painting. Grotewohl had been scheduled for arrest again on 20 July 1944, but the Gestapo was unable to locate him because he was now living off-the-grid. According to Heinz Voßke's 1979 biography of Grotewohl, this lifestyle allowed him to avoid being conscripted into the Volkssturm during the closing months of World War II.

After German defeat in World War II in May 1945, the country was occupied by the Allied forces and divided into four zones governed by the United States, the Soviet Union, the United Kingdom, and France, respectively. Grotewohl and several other former SPD politicians founded a branch of the re-established Social Democratic Party of Germany in the Soviet Occupation Zone, and he became the branch leader as Chairman of the Central Committee. Immediately after the war, the Soviets believed the Communist Party of Germany (KPD), rebuilt by the "Ulbricht Group" and led by Wilhelm Pieck, would naturally develop into the strongest political force in their zone with some guidance. However, Soviet leader Joseph Stalin and KPD deputy leader Walter Ulbricht began to push for a merger with the eastern SPD after the poor performance of communist parties in elections in Hungary and Austria in November 1945. The SPD in the Soviet zone faced increasing pressure from the Soviet Military Administration (SVAG) to merge with the KPD, despite historic animosity between the two parties. Unification was pushed by some members of Grotewohl's SPD in the Soviet zone and Berlin, under the belief that division between the main left-wing parties had led to Nazi rise to power. Grotewohl initially opposed the merger, but under duress from Ulbricht and SVAG soon yielded and became a proponent of a quick unification. Grotewohl's change of heart was fiercely opposed by Kurt Schumacher, a prominent member of the eastern SPD and anti-communist, who subsequently became leader of the western SPD after the merger.

In April 1946, the KPD and the eastern branch of the SPD merged as the Socialist Unity Party (SED), with Pieck and Grotewohl serving as co-chairmen. Grotewohl's hand appeared alongside Pieck's on the SED's "handshake" logo derived from the SPD-KPD congress establishing the party where he symbolically shook hands with Pieck. Grotewohl's position allowed him to avoid the systematic sidelining and exclusion of former SPD members that began soon after the merger. The few recalcitrant SPD supporters were condemned as "Agents of Schumacher" and shunted aside, accelerating a process that left the SED as essentially the KPD under a new name. Eventually, Grotewohl was one of the few holdovers from the SPD half of the merger to have a prominent post in the merged party.

In 1948, Grotewohl became Chairman of the constitutional committee of the German People's Council, the predecessor of the Volkskammer.