Major-General Malcolm Smith Mercer, CB (17 September 1859 – 3 June 1916) was a Canadian general, barrister and art patron who practiced law in Toronto and led the 3rd Canadian Division during the first two years of the First World War before he was killed in action at Mount Sorrel in Belgium. Mercer was an experienced militia commander and had demonstrated a great flair with training and organising the raw Canadian recruits during the opening months of the war.