Parrhasius (Greek: Παρράσιος) may refer to:
- Persons:
- Parrhasius (painter), a famous painter who worked in Athens in the late 5th century BC
- Janus Parrhasius (1470–1522), Italian humanist scholar
- Parrhasius (son of Lycaon), in mythology, a son of Lycaon, from whom Parrhasia (Arcadia) was believed to have derived its name
- Taxonomy:
- Parrhasius (butterfly), a butterfly genus