Robert Jordan – American university instructor of Spanish language and a specialist in demolitions and explosives.
Anselmo - Elderly guide to Robert Jordan.
Golz - Commander who ordered the bridge's demolition.
Pablo - Leader of a group of anti-fascist guerrillas.
Rafael – Incompetent, lazy guerrilla, and a gypsy.
María – Robert Jordan's young lover.
Pilar – Wife of Pablo. An aged but strong woman, she is the de facto leader of the guerrilla band.
Agustín – Foul-mouthed, middle-aged guerrilla.
El Sordo – Leader of a fellow band of guerrillas.
Fernando – Middle-aged guerrilla.
Andrés and Eladio – Brothers. Members of Pablo's band.
Primitivo – Young guerrilla in Pablo's band.
Joaquin – Enthusiastic teenaged communist, member of Sordo's band.