In Greek mythology, Hyllus (also Hyllas or Hylles) was the son of Heracles and Deianira, and husband of Iole.

Hyllus or Hyllos (Greek: Ὕλλος) – also, Phrygius – was the ancient name of a river of Asia Minor, a tributary of the river Hermus, in Lydia, flowing into Hermus from the north. (Homer Iliad xx. 392; Herodotus i. 80; Pliny v. 31.) In the time of Strabo (xiii. p. 626) the river was called Phrygius.

Hyllus is a spider genus of the Salticidae family (jumping spiders).