William Arthur Johnson (1816–1880) was an amateur biologist,[1] naturalist, microscopist, botanist, and ordained clergyman who lived in Canada.
[4] Johnson moved in Upper Canada in 1835, first settling in Port Maitland, Ontario, then to Toronto by 1848.
[5] Johnson became the major early influence for Osler at this time,[6][7] along with his friend James Bovell.
[8] A keen collector of both animal and vegetal specimens, Johnson was schoolmaster and rector of St. Philip's Church, Weston.
A collection of his microscopic and field sketches are conserved at the Osler Library of the History of Medicine, McGill University.