William Ronald Plager (July 6, 1945 — January 3, 2016) was a Canadian professional ice hockey defenceman.

Plager started his National Hockey League (NHL) career with the Minnesota North Stars in 1967.

Before playing in the National Hockey League, Plager played for the Peterborough Petes in Peterborough, Ontario, where he met his wife Donna Hickey.

After retiring from the NHL, Plager returned to Peterborough with Donna, sons William Jr., Brett and daughter Dara.

Plager retired from hockey and became a manager at Quaker Oats Peterborough plant and was head coach of Atom B/C IceKats, girls hockey teams in the Peterborough Girls Hockey Association.