Lethrinus mahsena, common names the sky emperor, mahsena emperor, and cutthroat emperor, is a species of emperor fish. It grows to 65 cm (26 in) in length, but is commonly found at between 35 and 45 cm (14 and 18 in). This fish may be yellow to greenish-blue or olive-grey, becoming paler toward the belly. It is a non-migratory, reef-associated fish that has a high commercial value.

Taxonomy Lethrinus mahsena was first formally described as Sciaena mahsena by the Danish zoologist Johan Christian Fabricius and published in Descriptiones animalium edited by Carsten Niebuhr. Fabricius based his description on the notes of Peter Forsskål who had died while on an expedition, which Neibuhr was also a member of, to Arabia. The Type locality was given as Ras Baridi north west of Yanbu in Saudi Arabia. Some authors place the genus Lethrinus in the monotypic subfamily Lethrininae, with all the other genera of Lethrinidae placed in the Monotaxinae, however, the 5th edition of Fishes of the World does not recognise the subfamilies traditionally accepted within the family Lethrinidae as valid. The family Lethrinidae is classified by the 5th edition of Fishes of the World as belonging to the order Spariformes.

Etymology Lethrinus mahsena has the specific name mahsena which is derived from the Arabic name for this fish in Saudi Arabia, Sjöûr mehseni.