Derek Harker (born January 7, 1951) is a Canadian former professional ice hockey defenceman. After three years in junior hockey with the Edmonton Oil Kings, he was selected by the St. Louis Blues in the fourth round (52nd overall) of the 1971 NHL Amateur Draft. Harker played the majority of his professional career with teams in the minor leagues (EHL, CHL, IHL, SHL, NAHL). During the inaugural 1972–73 season of the World Hockey Association, Harker played 28 games in that major league – one with the Alberta Oilers and 27 with the Philadelphia Blazers.