He was pronounced dead Sunday night at Ottawa Regional Hospital.
Although the cause of death is unknown, Sheardown did suffer from Alzheimer's disease.
During the 1979 Iranian hostage crisis, Sheardown helped six Americans hide and then escape the country.
The Americans were kept safe for months while staying at the private residences of Sheardown and then-Canadian ambassador to Iran, Ken Taylor.
Sheardown was the man who answered the call for help from the Americans fleeing an attack on the U.S. embassy in Iran.
The escape was dramatized in the 2012 movie Argo, starring Ben Affleck. However, Sheardown's son, Robin, said the movie left much of his father's story out, putting the spotlight on the CIA's Tony Mendez, who eventually got the Americans out of Iran.
"It's completely ignored all the Canadian involvement," Robin Sheardown said.
John Sheardown was born and raised in Windsor, Ont. and lived in Ottawa.
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