The Hyades were the nymphs that brought rain in Greek mythology. They were daughters of the Titan Atlas and either Pleione or the Oceanid Aethra, and had one brother, Hyas. They also were sisters of the Pleiades and the Hesperides.
According to the myth, their brother Hyas was killed while hunting, so they started crying from grief, which is how they brought rain on the earth. They were later transformed into a constellation of the same name. It is also believed that they helped in the upbringing of the god Dionysus, along with the Nysiads, the Lamides and the nymphs of the island Naxos. To show his gratitude, Dionysus later told Medea to give their youth back.