Alfred Vellucci
An Italian American, Vellucci was opposed to the idea that Leif Ericcson, rather than Christopher Columbus, discovered America. After a group of scholars from Harvard promoted the claim that Ericcson discovered America, he proposed a motion to the Cambridge City Council that officially renamed Harvard Square to Columbus Square. He also planted a large tree in front of the Harvard Lampoon Building, claiming that it was an eyesore and arguing that the "Harvard Lampoon" had insulted Italian Americans by claiming that the Irish discovered America. He feuded with the "Harvard Lampoon" for years. The paper often satirized him, one issue running an Alfred E. Neuman style picture of him on its cover. On one occasion, he unsuccessfully proposed a city ordinance declaring their headquarters a public urinal.
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.