The Mascarene parrot or mascarin (Mascarinus mascarinus) is an extinct species of parrot that was endemic to the Mascarene island of Réunion in the western Indian Ocean. The taxonomic relationships of this species have been subject to debate; it has historically been grouped with either the Psittaculini parrots or the vasa parrots, with the latest genetic study favouring the former group.

The Mascarene parrot was 35 cm (14 in) in length with a large red bill and long, rounded tail feathers. Its legs were red, and it had naked red skin around the eyes and nostrils. It had a black facial mask and partially white tail feathers, but the colouration of the body, wings and head in the living bird is unclear. Descriptions from life indicate the body and head were ash grey, and the white part of the tail had two dark central feathers. In contrast, stuffed specimens and old descriptions based on them indicate that the body was brown and the head bluish. This may be due to the specimens having changed colour as a result of ageing and exposure to light. Very little is known about the bird in life.

The Mascarene parrot was first mentioned in 1674, and live specimens were later brought to Europe, where they lived in captivity. The species was scientifically described in 1771. Only two stuffed specimens exist today, in Paris and Vienna. The date and cause of extinction for the Mascarene parrot is unclear. The latest account, from 1834, is considered dubious, so it is probable that the species became extinct prior to 1800, and may have become extinct even earlier.

The Mascarene parrot was first mentioned by the French traveller Sieur Dubois in his 1674 travelogue and only described a few times from life afterwards. At least three live specimens were brought to France in the late 18th century and kept in captivity, two of which were described while alive. Today, two stuffed specimens exist; the holotype, specimen MNHN 211, which is in the Muséum National d'Histoire Naturelle in Paris, while the other, specimen NMW 50.688, is in the Naturhistorisches Museum in Vienna. The latter specimen was bought from the Leverian Museum during a sale in London in 1806. A third stuffed specimen existed around the turn of the 18th century. The Mascarene parrot was scientifically described as Psittacus mascarinus (abbreviated as "mascarin") by the Swedish zoologist Carl Linnaeus in 1771. This name was first used by the French zoologist Mathurin Jacques Brisson in 1760 but was not intended as a scientific name. The name is a reference to the Mascarene Islands, which were themselves named after their Portuguese discoverer, Pedro Mascarenhas.

Early writers claimed the Mascarene parrot was found on Madagascar, an idea that led the French naturalist René Primevère Lesson to coin the junior synonym Mascarinus madagascariensis in 1831. His new genus name prevailed and, when the Italian zoologist Tommaso Salvadori combined it with the earlier specific name in 1891, it became a tautonym (a scientific name in which the two parts are identical). Lesson also included species of the Tanygnathus and Psittacula genera in Mascarinus, but this was not accepted by other writers. The following year, the German herpetologist Johann Georg Wagler erected the genus Coracopsis for the Mascarene parrot (which became Coracopsis mascarina under this system) and the lesser vasa parrot (Coracopsis nigra). The English zoologist William Alexander Forbes, believing that mascarinus was invalid as a specific name, since it was identical to the genus name, coined the new name Mascarinus duboisi in 1879, in honour of Dubois.

An unidentified dark parrot seen alive by the Swedish naturalist Fredrik Hasselqvist in Africa was given the name Psittacus obscurus by Linnaeus in 1758, who again synonymised it with the Mascarene parrot in 1766. Because of this association, some authors believed it was from the Mascarene Islands as well, but this dark parrot's description differs from that of the Mascarene parrot. This disagreement led some authors to use now-invalid combinations of the scientific names, such as Mascarinus obscurus and Coracopsis obscura. The unidentified parrot may have been a grey parrot (Psittacus erithacus) instead. Another unidentified parrot specimen, this one brown and housed in Cabinet du Roi, was described by the French naturalist Comte de Buffon in 1779 under his entry for the Mascarene parrot, in which he pointed out similarities and differences between the two. In 2007, the English palaeontologist Julian Hume suggested the possibility that this might have been a lesser vasa parrot, if not a discoloured old Mascarene grey parakeet (Psittacula bensoni). The specimen is now lost. English zoologist George Robert Gray assigned some eclectus parrot (Eclectus roratus) subspecies from the Moluccas to Mascarinus in the 1840s, but this idea was soon dismissed by other writers.

Subfossil parrot remains were later excavated from grottos on Réunion and reported in 1996. X-rays of the two existing stuffed Mascarene parrots made it possible to compare the remaining bones with the subfossils and showed these were intermediate in measurements in comparison to the modern specimens. The lesser vasa parrot was introduced to Réunion as early as 1780 but, though the subfossil parrot bones were similar to that species in some aspects, they were more similar to those of the Mascarene parrot and considered to belong to it.

The binomial name was emended from M. mascarinus to M. mascarin by the IOC World Bird List in 2016, to conform with how other species epithets by Linnaeus have been treated. In 2020, the International Commission on Zoological Nomenclature conserved the name M. mascarinus as a justified emendation of the original spelling.