In Navajo mythology, what is the name of the hero who killed the giants?

In Navajo mythology, the hero who killed the giants was Monster Slayer.

Monster Slayer is the English translation of Naayééʼ Neizghání, the elder of the Navajo, or Diné, Hero Twins. He and his younger brother, Born for Water, were born to protect the Diné from the monstrous beings known as the Anaye, who were devastating human communities.

The twins journeyed to meet their father, the Sun, and after surviving a series of trials, received powerful weapons, including lightning bolts. Monster Slayer performed much of the fighting, while Born for Water supported him through ritual knowledge and assistance. Their battles included the defeat of Yéʼiitsoh, the Big Giant, and other dangerous monsters.

The answer is sometimes confused with Born for Water or Changing Woman. Changing Woman is their mother, while Born for Water is Monster Slayer’s twin and partner—not the same hero. English spellings of the Diné name vary because Navajo words have been transliterated in different ways.