Tutankhamun (or Tutankhamen; ; Ancient Egyptian: twt-ꜥnḫ-jmn; c. 1341 BC – c. 1323 BC) was the antepenultimate pharaoh of the Eighteenth Dynasty of ancient Egypt. He ascended to the throne around the age of nine and reigned until his death around the age of nineteen. The most significant actions of his reign were reversing the societal changes enacted by his predecessor, Akhenaten, during the Amarna Period: Tutankhamun restored the traditional polytheistic form of ancient Egyptian religion, undoing the religious shift known as Atenism, and moved the royal court away from Akhenaten's capital, Amarna. Tutankhamun was one of few kings worshipped as a deity during his lifetime; this was usually done posthumously for most pharaohs. In popular culture, he is known for his vastly opulent wealth found during the 1922 discovery of his tomb, KV62, the only such tomb to date to have been found in near-intact condition. The discovery of his tomb is widely considered one of the greatest archaeological discoveries of all time.

His parentage is debated, as they are not attested in surviving inscriptions. DNA testing has identified his father as the mummy within tomb KV55, thought to be the pharaoh Akhenaten. His mother was identified as a mummy from tomb KV35, which was also his aunt, informally referred to as "The Younger Lady" but is otherwise unknown.

Tutankhamun took the throne under the unprecedented viziership of his eventual successor, Ay, to whom he may have been related. Within tomb KV21, the mummy KV21A was identified as having been the biological mother of Tutankhamun's two daughters — it is therefore speculated that this mummy is of his only known wife, Ankhesenamun, who was his paternal half-sister. Their two daughters were identified as the 317a and 317b mummies; daughter 317a was born prematurely at 5–6 months of pregnancy while daughter 317b was born at full-term, though both died in infancy. His names — Tutankhaten and Tutankhamun — are thought to have meant "living image of Aten" and "living image of Amun" in the ancient Egyptian language, with the god Aten having been replaced by the god Amun after Akhenaten's death. Some Egyptologists, including Battiscombe Gunn, have claimed that the translation may be incorrect, instead being closer to "the-life-of-Aten-is-pleasing" or "one-perfect-of-life-is-Aten" (the latter translation by Gerhard Fecht).

Tutankhamun enriched and endowed the priestly orders of two important cults, initiated a restoration process for old monuments that were damaged during the Amarna Period, and reburied his father's remains in the Valley of the Kings. Tutankhamun's health and early death are heavily debated. The most recent study suggests Tutankhamun had bone necrosis and a possible clubfoot, which may have rendered him dependent on assistive canes. This theory is disputed, as neither the canes nor his sandals show the kinds of the wear expected. He also had other health issues, including scoliosis, and had contracted several strains of malaria. He likely died of complications from a broken leg, possibly compounded by malaria.

In 1922, a team led by British Egyptologist Howard Carter in the Valley of the Kings excavated Tutankhamun's tomb, in an effort that was funded by British aristocrat George Herbert. The discovery of Tutankhamun's tomb received worldwide press coverage; with over 5,000 artifacts, it gave rise to renewed public interest in ancient Egypt, for which Tutankhamun's mask, now preserved at the Egyptian Museum, remains a popular symbol. The deaths of some individuals who were involved in the unearthing of Tutankhamun's mummy have been popularly attributed to the "curse of the pharaohs" due to the similarity of their circumstances. Some of his treasure has traveled worldwide with unprecedented response; the Egyptian government allowed tours beginning in 1961. Tutankhamun has, since the discovery of his intact tomb, been referred to as "King Tut" in colloquial terms.