Edward the Confessor died on 5 January 1066. He had no children. Three men wanted to be king of England. Each man thought he had the best claim to the throne. The next king of England would have to win it in a war. Who do you think had the best claim to the throne?
Harold was a powerful and rich English nobleman. According to the Anglo-Saxon Chronicle, Edward named Godwinson as his successor on his deathbed. The next day, the royal council, known as the Witan, met and declared Godwinson king. An English king was proclaimed by the Witan - this gave Harold Godwinson the only claim to the throne by right.
The Norman chroniclers reported that Edward had promised his distant relative, William, the throne in 1051. William was the only blood relative of Edward, but the English throne was not hereditary anyway. Claims that Edward promised the throne were probably made up by the rival sides after the event. The Bayeux Tapestry, which was made after the Conquest, shows Godwinson swearing an oath of support to William in a visit to Normandy in 1064. William was supported by the Pope.
Hardrada based his claim on the fact that his ancestor, King Cnut, had once ruled England (1016‒1035). He was helped by Godwinson's half-brother, Tostig.