Porphyrio is the swamphen or swamp hen bird genus in the rail family.

1/ Western swamphen (Xít, Porphyrio porphyrio)

2/ Grey-headed swamphen (Porphyrio poliocephalus) 
or Gray-headed swamp hen

3/ Black-backed swamphen (Porphyrio indicus)

Gruiformes, Gruidae: from the Latin word grus meaning "crane".
Rallidae: from rallus new Latin for rail, an aquatic bird.
The genus name Porphyrio comes from the Ancient Greek word πορφυρίων (porphurion), derived from πορφυρα (porphura), which means "purple". 
The term was adopted into Latin and New Latin, referring to a type of "swamphen" or "purple water-hen," a bird characterized by its striking purple or reddish-purple plumage.