Harold III Hardraada was a Norwegian king who reigned from 1046 to 1066. He was known for his military prowess and ambitious nature. He is most famous for his failed invasion of England in 1066, where he was defeated and killed at the Battle of Stamford Bridge. This event ultimately led to the Norman conquest of England by William the Conqueror. Harold III Hardraada is remembered as a significant figure in Norwegian and English history due to his military exploits and his role in the events leading up to the Norman conquest.