Berlin 1936:
Awarded to Berlin in 1931, a year before the Nazis rose to power, Hitler regarded the event as a tool for propaganda and an opportunity to promote Nazi ideology. Many countries considered boycotting the event in protest of anti-Semitism but ultimately did participate. Highlights included African-American athlete Jesse Owens winning four gold medals in various competitions to disprove Hitler’s theories on Aryan supremacy.
Mexico City 1968:
Once again, racial issues dominated the Games. South Africa was absent after the majority of black African nations threatened to boycott the Games if they were invited. During the medal ceremony of the 200m race two African-American sprinters, Tommie Smith and John Carlos raised their black-gloved fists – a symbol of the black-power movement. Both athletes were banned and sent home.
Munich 1972:
The Munich Games were overshadowed by the massacre of 11 Israeli athletes and coaches. During the second week of competition, Palestinian guerrillas gained access to the Olympic Village, and took the Israeli team hostage. The drama culminated in a bloody airport shootout which resulted in the deaths of all hostages and five out of the eighty hostage-takers
Last week I spoke to Lynne Evans who competed at the 1972 Games for the British archers. Hear her fascinating account of the events:
Moscow 1980:
A total of 50 nations boycotted the Games in protest of the Soviet invasion of Afghanistan in 1979. The Soviets retaliated four years later by boycotting the LA games.

Interesting to hear a first hand account of what happened. It must have been harrowing, but I dont believe we can ever separate politics from sport because politics pervades every area of our lives.