Xenus is a genus of waders containing only one member, Terek sandpiper (Xenus cinereus).

1/ Terek sandpiper (Choắt chân màng bé, Xenus cinereus) 
It is named after the Terek River which flows into the west of the Caspian Sea where it was first observed.
The genus name Xenus is from Ancient Greek xenos meaning "stranger"; the specific epithet cinereus is Latin for "ash-grey" from cinis, cineris, "ashes".