Roderigo, a Venetian who passionately desires Desdemona but is rejected by her, becomes a pawn in Iago's schemes. He is involved in a failed attempt to murder Cassio, where he both inflicts and receives wounds, ultimately meeting his end at Iago's hands.

In the Dramatis Personae, Roderigo is labeled as a gull, meaning he is an easily deceived person. He blindly trusts Iago and follows his every command. At the play's outset, Iago incites him to alarm Brabantio with the news of Desdemona's elopement with Othello. He then accompanies Iago to Cyprus, where he is used as a tool in Iago's plot to ruin Othello and Cassio. Following Iago's instructions, Roderigo picks a fight with Cassio during a general celebration and later attacks him in the dark, resulting in mutual injuries. Roderigo has given Iago money to negotiate with Desdemona on his behalf, believing that Iago's tasks are meant to eliminate Cassio and clear his path to Desdemona. Despite his reprehensible actions, Roderigo garners some sympathy due to his complete manipulation and ultimate betrayal by Iago, who kills him on a dark street to prevent him from revealing Iago's role in Cassio's wounding.

Roderigo frequently threatens to abandon his pursuit of Desdemona and stop financing Iago's interventions. Each time, Iago reassures him that Desdemona's attraction to Othello is merely physical and will soon fade. Iago advises Roderigo to build a strong financial foundation, repeatedly telling him to "Put money in thy purse" (I.iii.341-360), suggesting that once Desdemona's lust for Othello wanes, she will be drawn to a wealthy and stable man. In his frustration at not achieving his goal, Roderigo once exclaims, "It is silliness to live, when to live is torment" (I.iii.308). He apologizes for his foolishness but admits he lacks the "virtue" to change, to which Iago responds, "Virtue? a fig! 'tis in ourselves we are thus or thus" (I.iii.320). Iago insists that men shape their own destinies and are not bound by inherent qualities. This advice seems to renew Roderigo's determination, even as his threatened suicide underscores the depth of his longing for Desdemona.