| Role | Voice type | Premiere Cast, August 12, 1845 (Conductor: - ) |
|---|---|---|
| Alvaro, father of Gusmano, initially Governor of Peru | bass | Marco Arati |
| Gusmano, Governor of Peru | baritone | Filippo Coletti |
| Ovando, a Spanish Duke | tenor | Ceci |
| Zamoro, leader of a Peruvian tribe | tenor | Gaetano Fraschini |
| Ataliba, leader of a Peruvian tribe | bass | Michele Benedetti |
| Alzira, Ataliba's daughter | soprano | Eugenia Tadolini |
| Zuma, her maid | mezzo-soprano | Maria Salvetti |
| Otumbo, an American warrior | tenor | Francesco Rossi |
| Spanish officers and soldiers, Americans of both sexes | ||
Alzira, an Inca princess, receives an offer of marriage from the conquistadore Gusmano, but she rejects this offer. She is faithful to the memory of her lover, the Peruvian warrior Zamoro, who is presumed dead after battle with the Spaniards. However, Zamoro appears, to the joy of Alzira and the anger of Gusmano.
During the course of the opera, Gusmano succeeds his father, Alvaro, as governor of Peru. It is also revealed that Zamoro had saved the life of Alvaro, but this was to embarrass his enemies. Nonetheless, honour requires that Gusmano allow Zamoro to go free.
Zamoro then leads a fresh attack against the conquistadores, but is captured. Without hesitation, Gusmano condems Zamoro to death. In desperation, Alzira consents to marry Gusmano if he will spare Zamoro and release him. At the wedding for Alzira and Gusmano, Zamoro arrives and fatally stabs Gusmano. Before he dies, Gusmano forgives Zamoro and blesses the union of Alzira and Zamoro.