Userkaf (known in Ancient Greek as Οὐσερχέρης, Usercherês) was a pharaoh of ancient Egypt and the founder of the Fifth Dynasty. He reigned for seven to eight years in the early 25th century BC, during the Old Kingdom period. He probably belonged to a branch of the Fourth Dynasty royal family, although his parentage is uncertain; he could have been the son of Khentkaus I. He had at least one daughter and very probably a son, Sahure, with his consort Neferhetepes. This son succeeded him as pharaoh.

His reign heralded the ascendancy of the cult of Ra, who effectively became Egypt's state god during the Fifth Dynasty. Userkaf may have been a high-priest of Ra before ascending the throne, and built a sun temple, known as the Nekhenre, between Abusir and Abu Gurab. In doing so, he instituted a tradition followed by his successors over a period of 80 years. The Nekhenre mainly functioned as a mortuary temple for the setting sun. Rites performed in the temple were primarily concerned with Ra's creator function and his role as father of the king. Taken with the reduction in the size of the royal mortuary complex, this suggests a more concrete separation between the sun god and the king than in the preceding dynasties. After Userkaf's death, his temple was the subject of four building phases, during which it acquired a large obelisk.

Userkaf built a pyramid in Saqqara close to that of Djoser, a location that forced architects to put the associated mortuary temple in an unusual position, to the south of the pyramid. The latter was much smaller than those built during the Fourth Dynasty but the mortuary complex was lavishly and extensively decorated with fine painted reliefs. In addition to his own pyramid and temple, Userkaf built a smaller pyramid close to his for one of his queens, likely Neferhetepes. Although Userkaf was the object of a funerary cult after his death like the other Fifth Dynasty kings, his was relatively unimportant, and was abandoned after the end of the dynasty. Little is known of his activities beyond the construction of his pyramid and sun temple. The Old Kingdom royal annals record offerings of beer, bread and lands to various gods, some of which may correspond to building projects on Userkaf's behalf, including the temple of Montu in El-Tod where he is the earliest attested pharaoh. Beyond the borders of Egypt, a military expedition to Canaan or the Eastern Desert may have taken place, and trade contacts with the Aegean seem to have existed at the time. ^{[citation needed]}

The identity of Userkaf's parents is uncertain, but he undoubtedly had family connections with the rulers of the preceding Fourth Dynasty. Egyptologist Miroslav Verner proposes that he was a son of Menkaure by one of his secondary queens and possibly a full brother to his predecessor and the last king of the Fourth Dynasty, Shepseskaf.

Alternatively, Nicolas Grimal, Peter Clayton and Michael Rice propose that Userkaf was the son of a Neferhetepes, whom Grimal, Giovanna Magi and Rice see as a daughter of Djedefre and Hetepheres II. The identity of Neferhetepes's husband in this hypothesis is unknown, but Grimal conjectures that he may have been the "priest of Ra, lord of Sakhebu", mentioned in Westcar papyrus. Aidan Dodson and Dyan Hilton propose that Neferhetepes was buried in the pyramid next to that of Userkaf, which is believed to have belonged to a woman of the same name.

The location of the pyramid attributed to Neferhetepes, however, strongly suggests that she may instead have been Userkaf's wife. If so she should be identified with the Neferhetepes who is the mother of Userkaf's successor and likely son, Sahure. A relief from Sahure's causeway depicts this king and his queen together with the king's mother, identified as a Neferhetepes, which very likely makes her Userkaf's wife. Like Grimal, Jaromír Malek sees her as a daughter of Djedefre and Hetepheres II. Following this hypothesis, Mark Lehner also suggests that Userkaf's mother may have been Khentkaus I, an idea shared by Arielle Kozloff.

Dodson and Hilton argue that Neferhetepes is not given the title of king's wife in later documents pertaining to her mortuary cult, although they note that this absence is inconclusive. They propose that Userkaf's queen may have been Khentkaus I, a hypothesis shared by Selim Hassan. Clayton and Rosalie and Anthony David concur, further positing that Khentkaus I was Menkaure's daughter. Bernhard Grdseloff argues that Userkaf, as a descendant of pharaoh Djedefre marrying a woman from the main royal line—that of Khafre and Menkaure—could have unified two rival factions within the royal family and ended possible dynastic struggles. Alternatively, Userkaf could have been the high priest of Ra before ascending the throne, giving him sufficient influence to marry Shepseskaf's widow in the person of Khentkaus I.

Many Egyptologists, including Verner, Zemina, David, and Baker, believe that Sahure was Userkaf's son rather than his brother as suggested by the Westcar papyrus. The main evidence is a relief showing Sahure and his mother Neferhetepes, this being also the name of the queen who is believed to have owned the pyramid next to Userkaf's. An additional argument supporting the filiation of Sahure is the location of his pyramid in close proximity to Userkaf's sun temple. No other child of Userkaf has been identified except a daughter named Khamaat, mentioned in inscriptions uncovered in the mastaba of Ptahshepses.