The mouse-colored tyrannulet (Phaeomyias murina) is a species of bird in the family Tyrannidae, the tyrant flycatchers. It is monotypic within the genus Phaeomyias. It occurs in a wide range of scrubby and wooded habitats in tropical and subtropical South America, being absent from the southernmost part of the continent, the high Andes and dense rainforest. It also occurs in Panama and Costa Rica. It is generally common, but its small size and dull plumage results in it often being overlooked – or at least not identified, as it resembles several other tyrant flycatchers.