Final answer:
Nikita Khrushchev was the Soviet leader who demanded that the western powers leave Berlin during the Cold War, issuing ultimatums in 1958 and 1961 which were ignored by the West.
Step-by-step explanation:
The Soviet leader who demanded that the western powers leave Berlin was Nikita Khrushchev. Khrushchev served as the leader of the Soviet Union after Joseph Stalin's death in 1953, with a brief interim period under Georgy Malenkov. During the Cold War, Khrushchev made his demands regarding Berlin twice, firstly in 1958 and again in 1961. He saw West Berlin as a "thorn" in the Soviet's side due to its prosperity and the allowance of freedom which led many from the Eastern Bloc to escape to the West. These demands by Khrushchev were not heeded by Britain, France, and the United States, signaling a significant point of tension during this period.