William Aitchison JP (1880 or 1881 – 2 January 1957) was a New Zealand politician who served as the mayor of Invercargill in 1950.

In 1904 they came back to New Zealand permanently, and Aitchison began working at a grocery store in Christchurch.

[1] Aitchison was elected to the Invercargill City Council in 1941 and was re-elected in 1944, topping the poll and thus becoming deputy mayor.

[2] He did not intend to contest the election, but allowed his nomination to be submitted when no other councillor would step forward.

He became an elder of the church in June 1926 and taught at the Sunday school for 22 years.