Patrick Michael Dewan (December 23, 1890 – 1988) was an Ontario farmer and politician. He represented the Oxford electoral district in the Legislative Assembly of Ontario from 1934 to 1943 as a Liberal member.
He was born in Osgoode Township, Ontario, the son of John Joseph Dewan, and was educated at Willis Business College in Ottawa, the University of Ottawa, St. Francis Xavier University in Nova Scotia and the Ontario Agricultural College in Guelph. In 1921, Dewan married Margaret Olive Tierney. He served as alderman for Woodstock and was also secretary-treasurer of the Woodstock Agricultural Society. Dewan served as Minister of Agriculture in the provincial cabinet from 1937 to 1943.