William John Macdonald (29 November 1832 – 25 October 1916) was a Canadian merchant and politician. He migrated from the UK to the then separate colony of Vancouver Island aboard the Tory, a seven month voyage from 1850-51. He had been engaged as a clerk for the Hudson's Bay Company which at that time ruled Vancouver Island under a grant from the British. He served as mayor of Victoria, British Columbia in 1866, 1867 and 1871.
A Conservative, he was appointed to the Canadian Senate on 13 December 1871 on the recommendation of Sir John A. Macdonald. He represented the senatorial division of Victoria City, British Columbia until his resignation on 13 April 1915.