Haumea (minor-planet designation: 136108 Haumea) is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, who had discovered it that year in precovery images taken by the team in 2003. From that announcement, it received the provisional designation 2003 EL₆₁.

On 17 September 2008, it was named after Haumea, the Hawaiian goddess of childbirth and fertility, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. Nominal estimates make it the third-largest known trans-Neptunian object, after Eris and Pluto, and approximately the size of Uranus's moon Titania. Precovery images of Haumea have been identified back to 22 March 1955.

Haumea's mass is about one-third that of Pluto and 1/1400 that of Earth. Although its shape has not been directly observed, calculations from its light curve are consistent with it being a Jacobi ellipsoid (the shape it would be if it were a dwarf planet), with its major axis twice as long as its minor. In October 2017, astronomers announced the discovery of a ring system around Haumea, representing the first ring system discovered for a trans-Neptunian object and a dwarf planet.

Haumea's gravity was until recently thought to be sufficient for it to have relaxed into hydrostatic equilibrium, though that is now unclear. Haumea's elongated shape, together with its rapid rotation, rings, and high albedo (from a surface of crystalline water ice), is thought to be the consequences of a giant collision, which left Haumea the largest member of a collisional family (the Haumea family) that includes several large trans-Neptunian objects and Haumea's two known moons, Hiʻiaka and Namaka.

Two teams claim credit for the discovery of Haumea. A team consisting of Mike Brown of Caltech, David Rabinowitz of Yale University, and Chad Trujillo of Gemini Observatory in Hawaii discovered Haumea on 28 December 2004, on images they had taken on 6 May 2004. On 20 July 2005, they published an online abstract of a report intended to announce the discovery at a conference in September 2005.

At around this time, José Luis Ortiz Moreno and his team at the Instituto de Astrofísica de Andalucía at Sierra Nevada Observatory in Spain found Haumea on images taken on 7–10 March 2003. Ortiz emailed the Minor Planet Center with their discovery on the night of 27 July 2005.

Brown initially conceded discovery credit to Ortiz, but came to suspect the Spanish team of fraud upon learning that the Spanish observatory had accessed Brown's observation logs the day before the discovery announcement, a fact that they did not disclose in the announcement as would be customary. Those logs included enough information to allow the Ortiz team to precover Haumea in their 2003 images, and they were accessed again just before Ortiz scheduled telescope time to obtain confirmation images for a second announcement to the MPC on 29 July. Ortiz later admitted he had accessed the Caltech observation logs but denied any wrongdoing, stating he was merely verifying whether they had discovered a new object.

IAU protocol is that discovery credit for a minor planet goes to whoever first submits a report to the MPC (Minor Planet Center) with enough positional data for a decent determination of its orbit, and that the credited discoverer has priority in choosing a name. However, the IAU announcement on 17 September 2008, that Haumea had been named by a dual committee established for bodies expected to be dwarf planets, did not mention a discoverer. The location of discovery was listed as the Sierra Nevada Observatory of the Spanish team, but the chosen name, Haumea, was the Caltech proposal. Ortiz's team had proposed "Ataecina", the ancient Iberian goddess of spring; as a chthonic deity, it would have been appropriate for a plutino, which Haumea was not.