Despite her brief appearance on stage, Bianca plays a significant role in the progress of Iago's scheme to make Othello believe that his wife Desdemona is cheating on him with Cassio.

[1] In Act 3, Scene 3, Iago reveals to the audience that, having surreptitiously obtained the handkerchief that Othello had originally given Desdemona as a lover's token, he will lose it in Cassio's lodging.

Midway through Act 4, Scene 1, and prior to Bianca's entrance, Othello has been secretly observing a bawdy discussion between Iago and Cassio about the latter's sexual exploits with a young woman.

Thanks to Iago's impeccable planning (and some bad luck), neither speaker mentions the name of the woman in question; it is in fact Bianca, but Othello tragically assumes it to be his wife, Desdemona.

Bianca was played by Doris Dowling in Orson Welles's 1952 adaptation, Sheila Reid in Laurence Olivier's 1965 version, and Indra Ové in a 1995 feature film.