The blue-breasted fairywren (Malurus pulcherrimus), or blue-breasted wren, is a species of passerine bird in the Australasian wren family, Maluridae. It is non-migratory and endemic to southern Western Australia and the Eyre Peninsula in South Australia. Exhibiting a high degree of sexual dimorphism, the male adopts a brilliantly coloured breeding plumage, with a bright blue crown, ear coverts and upper back, red shoulders, contrasting with a dark blue throat, grey-brown tail and wings and pale underparts. Non-breeding males, females and juveniles have predominantly grey-brown plumage. No separate subspecies are recognised.