The Mercury Eight is an automobile that was produced by the American manufacturer Ford Motor Company under their now defunct division Mercury between 1939 and 1951. The debut model line of the Mercury division, Ford slotted the full-size Mercury Eight between the Ford Deluxe model lines and the Lincoln. In total, Ford assembled three generations of the Eight.

Mercury was a brand of mid-priced automobiles produced by American manufacturer Ford Motor Company between 1938 and 2011 with 1939 being the first model year. It stood as its own line within Ford until 1945, and thereafter formed half of Ford's Lincoln-Mercury Division. Created by Edsel Ford in 1938 to bridge the gap between the Ford and Lincoln model lines, its principal competition was General Motors' Buick and Oldsmobile divisions, and Chrysler Corporation's DeSoto and Chrysler brands.