William J. P. MacMillan

William Joseph Parnell MacMillan
18th Premier of Prince Edward Island
In office
October 14, 1933  August 15, 1935
Monarch George V
Lieutenant Governor Charles Dalton
George DesBrisay DeBlois
Preceded by James D. Stewart
Succeeded by Walter M. Lea
Leader of the Conservative/Progressive Conservative of Prince Edward Island
In office
1933–1948
Preceded by James D. Stewart
Succeeded by Reginald Bell
Personal details
Born March 24, 1881
Clermont, Prince Edward Island
Died December 7, 1957 (aged 76)
Charlottetown, Prince Edward Island
Nationality Canadian
Political party Conservative/Progressive Conservative
Spouse(s) Mary B. Macdonald (m. 1909)
Letitia Macdonald (nee Roberts (m. 1922)
Children Mary Dorothea, Catherine Bernadette, Joseph, Stephen, Nora, and Allan
Residence Clermont, Prince Edward Island
Alma mater Prince of Wales College
McGill University
Occupation physician and surgeon
Profession Politician
Cabinet Minister without Portfolio (1923–1927)
Minister of Education (1931–1933)
Minister of Public Health (1931–1935)
Provincial Secretary-Treasurer (1933–1935)
Religion Roman Catholic

William Joseph Parnell MacMillan (March 24, 1881 December 7, 1957) was a physician and Prince Edward Island politician.

Born in Clermont, MacMillan was a graduate of Prince of Wales College and the McGill University Faculty of Medicine.

After running a medical practice for several years, MacMillan entered politics in 1923 winning a seat in the provincial legislative assembly as a Conservative. In 1932 he became the province's first minister of health and education. As minister he rebuilt Prince of Wales College and the Provincial Mental Hospital which had both been destroyed by fire. He also secured a Carnegie Foundation endowment that enabled the government to establish a provincial library system.

When James D. Stewart became ill, MacMillan served as acting premier and then became the 18th Premier when Stewart died in 1933. MacMillan's government implemented relief programs and increasing government spending to help dampen the impact of the Great Depression. Nevertheless, his government was swept from power in the 1935 election which saw the Liberals capture every seat in the legislature. He returned to the legislature in 1939 and remained leader of the Conservative Party until the late 1940s and a member of the legislature until he lost his seat in the 1955 election.

MacMillan was named the province's lieutenant governor on November 22, 1957 but died before being sworn in.