Conway MacMillan (August 26, 1867 – June 5, 1929) was an American botanist from Minnesota.

MacMillan was born in Hillsdale, Michigan.

Macmillan worked at the University of Minnesota until he resigned over the problems with Josephine Tilden's "Minnesota Seaside Station" in Canada.

MacMillan headed the research station where 25 to 30 students would study each summer.

Under his leadership the land gathered a number of buildings and a three-mile road was built from Port Renfrew to allow access.