Sources for Othello
The principal source for Othello is a story by an Italian author, Giovanni Battista (or Giambattista) Giraldi, who is also known as Cinthio or Cinzio, in his collection of novellas entitled Hecatommithi,(3.7), published in Venice in 1565.  The work was published in a French translation by Gabriel Chappuys in 1584. Cinthio named none of his characters except for his heroine, called ‘Disdemona’, a name of ‘unlucky augury’. 
Shakespeare took most of the characters and plot of Othello from Cinthio. However, the first act of Othello represents an elaboration of a single line in Cinthio, telling us that Disdemona’s family did not approve of her match with the Moor. Shakespeare uses the first act to introduce Brabantio, Desdemona’s distraught father, and to show us Iago’s manipulation of Brabantio as well as of Roderigo, a character who does not appear in Cinthio. Another important addition is Othello’s revelation of his use of tales about his travels and deeds in courting Desdemona. This highlights both Othello’s boldness and his tender and lyrical side, while showing the use he makes of the power of words, to which he will in the end himself prove tragically vulnerable. Shakespeare’s expansion of Cinthio’s brief introduction to the principal characters thus sets the scene for the intricate psychological drama that is to follow.
Shakespeare also changed details of Cinthio’s plot. For example, in Cinthio virtually all of the action takes place in Cyprus; and the Corporal (‘capo di squadra’ in Italian), who becomes Cassio in Othello, recognises Disdemona’s handkerchief and attempts to return it to her. Most notably, Shakespeare modifies Cinthio’s ending, in which the Ensign (who becomes Iago in Othello) is the one who, with the Moor’s consent, beats Disdemona to death. Shakespeare’s characters are more complex than Cinthio’s, and often at odds with themselves. For example, while Cinthio’s Ensign is motivated primarily by frustrated lust, Iago is resentful and cynical,  claiming to prefer gain to passion,  and yet, as the play goes on, behaves in a way that is both obsessive and uncontrolled.
Other possible sources for Othello include a story of wife-murder motivated by jealousy, set during the Turkish wars, from Belleforest’s Histoires Tragiques (1561), appearing in English in Certaine Tragicall Discourses of Bandello, translated by Geoffrey Fenton (1567).  Sources like these could have provided Shakespeare with plot elements; others he tapped into to enrich the background and descriptive detail of Othello. Pliny the Elder’s Naturalis Historia, in English called The historie of the world: Commonly called, the Natvrall historie of C. Plinivs Secundvs, Tr. into English by Philemon Holland, doctor in physicke (London: Islip, 1601), furnished descriptions of the strange and magical places Othello mentions, where ‘Arabian trees’ drop ‘medicinable gum’,  or where there are ‘cannibals that each other eat,/ The Anthropophagi, and men whose heads/ Do grow beneath their shoulders’. 
The sixteenth-century conflict between Christian Europe and the Ottoman Empire provided the background for Othello. One possible source was Richard Knolles, who in The Generall Historie of the Turkes (1603), recounted the efforts of the Venetians to defend the wealthy and ‘pleasant’ island of Cyprus against the ‘gallies’ and ‘galliots’ of the Turkish fleet.  The Battle of Lepanto, in 1571, between the ‘Holy League’, of which Venice was a part, and the Ottoman fleet, in which the Spanish writer Miguel de Cervantes fought for the Christian alliance, was immortalised in poetry by James VI and I in 1585. The poem was reprinted in His Maiesties poeticall exercises at vacant Houres (Edinburgh: Robert Walde-Graue, 1591), appending a French translation by Du Bartas. James included rousing descriptions of battle : ‘Whill time a Turk with arrow doth,/ Shoot through a Christians arme,/ A Christian with a Pike dooth pearce/ The hand that did the harme’ (Lepanto, ll. 716-19). This recalls Othello’s memory of smiting a ‘turbanned Turk’ who ‘beat a Venetian’ during a battle (5.2.351-2). Shakespeare’s knowledge of the wars would have been enriched by sources like these, and his wide reading lent liveliness and verisimilitude to the setting of his play.
1. For a fuller discussion of Shakespeare’s use of Cinthio’s tale, and a translation of Cinthio, cf. Geoffrey Bullough, Narrative and Dramatic Sources of Shakespeare, 8 vols (London: Routledge, 1957-75), VII, Major Tragedies: Hamlet, Othello, King Lear, Macbeth (1973, 1978), pp. 193-265, and William Shakespeare, Othello, ed. by E. A. J. Honigmann, The Arden Shakespeare, 3rd edn (London: Thomson Learning, 1997, 2004), pp. 1-111, esp. pp. 12-13, and pp. 368-87. Return to text
7. Othello, 1.3.144-6, p. 144. Cf. William Shakespeare, Othello, ed. by Norman Sanders, The New Cambridge Shakespeare (Cambridge: CUP, 1984, 1987), p. 10. Return to text
8. Cited in Bullough as a ‘probable source’ for Othello, pp. 262-5. However, since Bullough gives the date of Knolles’ work as 1603, this identification would depend on a late date (1603-4) for the writing of Othello: Honigman (Othello, Arden 3rd edn), argues for an early date of late 1601-1602 for Othello. Return to text