Einar Gerhardsen (May 10, 1897 - September 19, 1987) was a Norwegian politician from the Labour Party. He was Prime Minister of Norway from 1945 to 1951, from 1955 to 1963 and from 1963 to 1965.

Einar Gerhardsen was born in Asker in 1897, at the time a rural community west of Oslo. He became politically active as a road worker in the socialist movement in the 1920s with a radical orientation. He was convicted of subversive activity several times until moving into mainstream activities in the 1930s. During World War II, Gerhardsen took part in the resistance against Nazi occupation and was interred in concentration camps in Grini in Norway and at Sachsenhausen.

He was relatively unknown among Norwegian politicians when he formed the first elected government after the war.

During and after he held office he was a greatly respected figure in the eyes of the people, even amongst those not sharing his social democratic views. Often referred to as "Landsfaderen" (meaning Father of the Nation) for his great achievements in building the modern Norway after World War II. Norway changed from being a rather weak, poor and underdeveloped nation into a prosperous and industrialized state in his period. Poverty, lack of housing, slums and unemployment virtually became non-existent as a result of the planned policy of industrialisation, investing in infrastructure and education, redistributing wealth through high progressive taxation and regulating finance. He also led the formation of a foreign policy based on Norway's membership in NATO. He retired from his political career in 1969, to spend more time with his wife and beloved dog, "Gro", but continued to influence public opinion through writings and speeches.

In November of 1962, there was an explosion in the Kings Bay mine in Svalbard, in which 11 mine workers died. The Gerhardsen government was accused of not complying with laws established by the Norwegian parliament. After a 72-hour televised debate, a vote of no-confidence passed with the support of the predecssor of today's Socialist Left Party under the leadership of Finn Gustavsen . The uninterrupted Social-Democratic reign in Norway after World War II came to an end with a scandal.

Gerhardsen's political legacy is still an important force in Norwegian politics, although some of the social policies have been revised and the economy oriented more toward petroleum and services (See also Economy of Norway). Although many of the Gerhardsen-era's policies are widely credited for creating a viable welfare state in Norway, others are more controversial.

|- style="text-align: center;" | width="30%" |Preceded by:
Oscar Torp | width="40%" style="text-align: center;" |Prime Minister of Norway
1955–1963 | width="30%" |Succeeded by:
John Lyng

|- style="text-align: center;" | width="30%" |Preceded by:
John Lyng | width="40%" style="text-align: center;" |Prime Minister of Norway
1963–1965 | width="30%" |Succeeded by:
Per Borten

¹Nygaardsvold, along with his cabinet as well as the entire parliament, resided in exile in London during WWII while Norway was occupied by Nazi-Germany. In parts of this period Vidkun Quisling, leader of non-democratic political party Nasjonal Samling, assumed a degree of formal power, but in reality the country was governed by the occupants, represented by Reichskommissar Josef Terboven.