Alfred "Centennial" Johnson (1846–1927) was a Danish-born fisherman from Gloucester, Massachusetts.
In 1876, in a 20-foot (6.1 m) sailing dory, he made the first recorded single-handed crossing of the Atlantic Ocean, landing at Abercastle in west Wales as a celebration of the first centennial of the United States.
Local author Rob Morris has also written a book about the crossing called Alfred "Centennial" Johnson.Johnson's dory, Centennial, is now in the collection of the Cape Ann Museum in Gloucester, Massachusetts.
It is frequently displayed alongside Howard Blackburn's sloop Great Republic, a vessel which was also used in a single-handed trans-Atlantic crossing.