Royal blue is a colour.
Royal Blue may also refer to:
Royal Blue (train), a passenger train between New York City and Washington, D.C., United States Royal Blue (yacht), a maxi yacht Royal Blue, Tennessee, a community in Campbell County, Tennessee, United States Royal Blue (pigeon), an RAF messenger pigeon of World War II Myscelia cyaniris or royal blue, a brush-footed butterfly of Central and northern South America Orachrysops regalis or royal blue, a butterfly in the family Lycaenidae found in South Africa
See also Royal Blue Coach Services, a former coach operator in England