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.
Sebastian Cabot (explorer)
According to "Cartografía Marítima Hispana", Sebastian Cabot included a handwritten text in Latin on his famous map of North America (published in Antwerp, 1544) claiming to have discovered North America with his father in 1494, three years before his father's voyage. Sancho Gutierrez repeated this text in Castilian on his 1551 map. 
Placed next to the border of North America, the text reads:
This land was discovered by Johannes Caboto, venetian and Sebastian Caboto, his son, in the year of the birth of our Lord Jesus Christ MCCCCXCIV, 24th of June in the morning. They put to it the name 'prima terra vista' and [...] This big island was named Saint John, as it was discovered on Saint John holiday. People there wander wearing animal furs. They use bow and arrow to fight, javelins and darts and wooden batons and slings. This is a very sterile land, there are a lot of white bears and very big deers, big as horses, and many other animals. As well there are infinite fish: plaices, salmons, very long soles, 1 yard long and many other varieties of fish. Most of them are called cod. And there are also black hawks, black as ravens, eagles, partridges and many other birds.