Papilio plagiatus, the mountain mimetic swallowtail, is a butterfly of the family Papilionidae.

[3] Papilio plagiatus looks very similar to Papilio cynorta, but the male has pure white discal bands, with no traces of ivory, and the female's patterns are a bit different.

The hind wings are dark brown at the base and in the margin and cream in the discal part.

The hindwings have similar patterns to those of the obverse but the base is distinctly orange and bears two black dots 1, 2 .

In both sexes the body is black and the thorax bears white macules.