[1] Unseen characters have been used since the beginning of theatre with the ancient Greek tragedians, such as Laius in Sophocles' Oedipus Rex and Jason's bride in Euripides' Medea, and continued into Elizabethan theatre with examples such as Rosaline in Shakespeare's Romeo and Juliet.
[2] However, it was the early twentieth-century European playwrights Strindberg, Ibsen, and Chekhov who fully developed the dramatic potential of the unseen character.
[3] In a study of 18th-century French comedy, F. C. Green suggests that an "invisible character" can be defined as one who, though not seen, "influences the action of the play".
They originally intended that Maris would appear after several episodes, but were enjoying writing excuses for her absence so eventually it was decided she would remain unseen, and after the increasingly eccentric characteristics ascribed to her, no real actress could realistically portray her.
[6] Unseen characters occur elsewhere in drama, including the plays of Eugene O'Neill, Tennessee Williams, and Edward Albee.