Ria Antoniou (Greek: Ρία Αντωνίου, born July 14, 1988) is a Greek beauty pageant titleholder and the 2nd runner-up in Star Hellas 2008. Antoniou failed to be crowned Miss Greece Universe or World. Being half Peloponnesian, she entered and won the "Miss Peloponnese" pageant in 2007. Antoniou represented Greece in the "Model of the World" pageant and placed as a 2nd runner-up.
Months after the pageant, Antoniou was appointed by the Star Hellas Organization to represent Greece in Miss Earth 2008 on November 9, 2008, in Angeles City, Pampanga, Philippines. She failed to make the cut.