Callias was an Athenian comic poet active in the 5th century BCE during the period of Old Comedy. He is often identified as Callias, son of Hipponicus, a member of a famously wealthy and prominent Athenian family. The date of his career is firmly established by his competition against major playwrights like Aristophanes; ancient records indicate he defeated Aristophanes' first version of The Clouds at the City Dionysia in 423 BCE.

He is credited with a small number of comedies, of which only two titles survive with certainty from fragments and ancient references: Pedetai (The Prisoners) and Grammatike Theoria (The Scholarship Tour or The Alphabet Show). Both plays are lost and known only through fragments.

Callias is historically significant as a successful contemporary of Aristophanes, illustrating the vibrant competitive atmosphere of Athenian theater. His victory over the original Clouds is a notable event in the history of comedy. His play Grammatike Theoria is of particular interest to scholars. According to modern interpretations, its fragments suggest it was a satire of intellectual and sophistic trends, possibly featuring a contest between letters of the alphabet. This places his work within a subgenre of Old Comedy that engaged with contemporary linguistic and philosophical debates. As a probable aristocrat, his comedies provide a perspective from within the social elite that was often the target of comic ridicule.