Harald Hardrada was born on September 25, 1015, then in 1046 was crowned kind of Norway. Harald thought that he was the rightful heir to the throne because he was a descendant of King Canute of England and he also claimed that Edward had promised his family the throne
Harold Godwinson born 1020, Anglo-Saxon of England had the strongest claim to the throne because it's believed that he was promised the throne by Edward himself as he lay dying. Harold swore an oath to Edward that soon a witan found invalid because it was made under the threat of death.
William of Normandy was a distant cousin of Edward the Confessor, he claimed that Edward and Harold had both promised him the throne. English supporters of Harold disagreed with this and challenged it as well.