Rt. Hon. John Whitney (Jack) Pickersgill (June 23, 1905 - November 14, 1997) was a Canadian civil servant and politician.

Pickersgill was born in Norfolk County, Ontario, and raised in Manitoba. Educated at the University of Manitoba and University of Oxford, Pickersgill taught history in Winnipeg before joining the Department of External Affairs in Ottawa. He was soon working at the Prime Minister's Office as Assistant Private Secretary to Prime MInister William Lyon Mackenzie King. In 1945 he became Special Assistant to the Prime Minister and was officially in charge of the Prime Minister's Office. He stayed on to work for King's successor, Louis St. Laurent, and became Clerk of the Privy Council in 1952. He was a senior and trusted adviser to both Prime Ministers and "Clear it with Jack" was the byword on Parliament Hill for years.

Pickersgill entered the Canadian House of Commons as Liberal MP for Bonavista-Twillingsgate, Newfoundland as a result of the 1953 Canadian election. He entered the Canadian Cabinet as Secretary of State for Canada in 1953 and was promoted to Minister for Citizenship and Immigration in 1954. When the Liberal government was defeated in the 1957 Canadian election, Pickersgill was re-elected as an MP and became a leading tormentor of the new government of John George Diefenbaker from the opposition benches.

With the 1963 Canadian election and the coming to power of Lester Pearson as Prime Minister, Pickersgill returned to Cabinet, first as Secretary of State for Canada and Government House Leader, and then as Minister of Transport. In 1967 he retired from politics to become president of the Canadian Transport Commission .

In 1970 he was made a Companion of the Order of Canada.

He was later bestowed the title Right Honourable, usually reserved for Prime Ministers, Governors-General and Chief Justices as recognition of his service.