The Napean are a partially empathic race from the Alpha or Beta Quadrant. Presumably, they are physically similar to most humanoids excepting their having a large, leaf-shaped forehead ridge.
Starfleet Lieutenant Daniel Kwan was half-Human and half-Napean hybrid. (TNG: "Eye of the Beholder")
A crewmember serving on board the Template:ShipClass USS Lexington was also of Napean descent. (DS9: "Explorers")
Another Napean was part of Kasidy Yates crew aboard the Xhosa. (DS9: "Family Business")
According to Daniel Kwan's personnel file seen in the episode, Daniel Kwan was a native of Psi Upsilon IV. This may suggest that the Psi Upsilon system is the homeworld of the Napean species.
Napeans have appeared in several novels, and in the non-canon game "Star Trek: Elite Force II", a Napean is the chief of security for Starfleet Academy.