Hetairai (/hɪˈtaɪraɪ/; sing. hetaira /hɪˈtaɪrə/; also hetaera /hɪˈtɪrə/, pl. hetaerae /hɪˈtɪriː/; Ancient Greek: ἑταίρα, "companion," pl. ἑταῖραι) were a type of prostitute in ancient Greece.
Traditionally, historians of ancient Greece have distinguished between hetairai and pornai, another class of Greek prostitute. In contrast to pornai, who provided sex for a large number of clients in brothels or on the street, hetairai were thought to have had only a few men as clients at any one time, to have had long-term relationships with them, and to have provided companionship and intellectual stimulation as well as sex. For instance, Charles Seltman wrote in 1953 that "hetaeras were certainly in a very different class, often highly educated women".