Philaeus may refer to:
In Greek mythology:
- Philaeus (son of Ajax), a son of Ajax and Lysidice
- Philaeus, a son of Munichus and Lelante
In biology:
- Philaeus, a spider genus
- Philaeus chrysops, a species in this genus
- Philaeus multicolor, a synonym for Paraphidippus aurantius
- Philaeus farneus, a synonym for Phidippus audax