Leif Erikson
Leif Erikson or Leif Ericson ( 970 – c. 1020) was a Norse explorer from Iceland. He was the first known European to have set foot on continental North America (excluding Greenland), before Christopher Columbus. According to the Sagas of Icelanders, he established a Norse settlement at Vinland, tentatively identified with the Norse L'Anse aux Meadows on the northern tip of Newfoundland in modern-day Canada. Later archaeological evidence suggests that Vinland may have been the areas around the Gulf of St. Lawrence and that the L'Anse aux Meadows site was a ship repair station.
Alonso Sánchez
After the discovery of America several rumors started to spread especially among the conquistadores, claiming that America had not been discovered by Columbus, but that its existence was known at least 20 years before 1492. Bartolomé de las Casas had indeed heard several of those claims, but limited himself to record them.