Stichomythia (Ancient Greek: στιχομυθία, romanized: stikhomuthía) is a technique in verse drama in which sequences of single alternating lines, or half-lines (hemistichomythia) or two-line speeches (distichomythia) are given to alternating characters. It typically features repetition and antithesis. The term originated in the theatre of Ancient Greece, though many dramatists since have used the technique. Etymologically it derives from the Greek stikhos ("row, line of verse") + muthos ("speech, talk").

Stichomythia is particularly well suited to sections of dramatic dialogue where two characters are in violent dispute. The rhythmic intensity of the alternating lines combined with quick, biting ripostes in the dialogue can create a powerful effect.

Stichomythia originated in Greek drama, where, in the early plays of Aeschylus it applies to exchanges between the protagonist and the chorus. Adolf Gross concludes that stichomythia developed from choral response. J. Leonard Hancock differs in this regard, not finding overwhelming evidence for any particular origin theory, but admitting that the role of musical symmetry must have been significant. Instead he finds that the trends, within Ancient Greek aesthetics, toward agonistic expression, subtlety in language, and love of symmetry, helped to give rise to stichomythia as a popular dialogue device.

Senecan stichomythia, while ultimately derived from Athenian stichomythia (as Roman theatre is derived from Greek theatre generally) differs in several respects. First, Seneca uses the technique less than all but the earliest extant pieces of classical Greek tragedy. Secondly, the stichomythic form found in Seneca is less rigid. Finally, and most substantially, Seneca's tragedies are much more prone to revolve around literary quibbles, even leaving aside the plot of the play for entire sections while the characters engage in an essentially linguistic tangent.

Renaissance Italian and French drama developed in many respects as an imitation of the classic drama of the Greeks and Romans. Stichomythic elements, however, were often absent. Where they did occur, they tended to follow the lead of Seneca in using “catchwords” as launching points for each subsequent line.

Modern theatre rarely uses verse, so any construct that depends on verse, such as stichomythia, is also rare. Where a form of stichomythia has been used, the characters involved are typically building subsequent lines on the ideas or metaphors of previous lines, rather than words.

In terms of character relationships, stichomythia can represent interactions as mundane as question-and-answer exchanges, or as tense as heated rapid-fire arguments. While the equal line lengths can create a sense of equality of voice between the characters, stichomythia can also feature one character silencing another with a vociferous rebuff, especially where one character's line interrupts the other's.

In terms of how stichomythia moves forward as a section of dialogue, the Ancient Greeks tended to favor subtle flavorings and reflavorings of grammatical particles, whereas Senecan (and by extension Renaissance) stichomythic passages often turned on verbal minutiae or “catchwords”. Modern theatre, on the other hand, uses the technique in such a manner that the characters use each line to add depth to a shared idea or metaphor.