Don Diego de la Vega (portrayed by Guy Williams) is depicted as a former University student, newly recalled by his father from Spain to his home outside El Pueblo de Nuestra Señora Reina de los Ángeles sobre El Rio Porciuncula (later shortened as Los Angeles). Just before reaching California, Diego learns of the tyranny of Captain Monastario from the ship's captain, and realizes that his father, Don Alejandro (George J. Lewis), summoned him to help fight this injustice. Although he won medals for his fencing back in Spain, Diego decides that his best course of action is to conceal his ability with a sword, and to affect the demeanor of a milquetoast intellectual rather than a decisive man of action. His alter ego, Zorro operates primarily at night, taking the direct action that Diego cannot. This deception does not always sit well with Diego, especially as it affects his relationship with his disappointed father. In reality, Diego relies heavily on his wits, both with and without the mask on. Later in the series, Diego emerges as a respected figure in his own right, a clever thinker and loyal friend who just happens to be hopeless at swordplay.
The character's name in Johnston McCulley's writing and previous adaptations was Diego Vega; the Disney version expands the name to Diego de la Vega, an innovation retained in some subsequent versions of the story.
- Diego's singing voice is supplied by Bill Lee of the Mellomen.
- El Zorro means The Fox in Spanish
- For the first time in any version of Zorro, Don Diego is a poor fencer. Diego never tells anybody about the fencing medals and trophies he earned while at school in Madrid. Whenever Diego is forced to fence, he fences as awkwardly as possible.
- Through out the series five people have succeeded in figuring out Diego's secret identity but only two lived to tell the tale. Those two were Diego's father and Capitan Monasterio, although no one believed Monasterio and he was sent to prison. The other four weren't so lucky since they died after finding out about Diego's double life. Don Juan Ortega pulled off Diego's mask just before falling to his death, Andres Felipe Basilio found out and donned the Zorro attire only to be shot by Perico Capitan Mendoza, who had direct orders to shoot Zorro on sight.