Siim Kallas is an Estonian politician, former Prime Minister of Estonia, and former European Commissioner, as well as a former member of the Communist Party of the Soviet Union.

The prime minister of Estonia is the head of government of the Republic of Estonia. The prime minister is nominated by the president after appropriate consultations with the parliamentary factions and confirmed by the parliament (Riigikogu). In case of disagreement, the parliament can reject the president's nomination and choose their own candidate. In practice, since the prime minister must maintain the confidence of parliament in order to remain in office, they are usually the leader of the senior partner in the governing coalition. The current prime minister is Kaja Kallas of the Reform Party. She took the office on 26 January 2021 following the resignation of Jüri Ratas.