The name Alfonso has its origins in the medieval Iberian Peninsula, derived from the Germanic name Āḷf-funz, meaning "ready for battle." It combines the elements "alf" (elf or supernatural being) and "funz" (ready or willing). The name gained prominence during the Christian Reconquista of the Iberian Peninsula from the Muslim Moors.

One of the earliest recorded instances of the name Alfonso dates back to the 8th century, when Alfonso I (693-757) ascended to the throne of the Kingdom of Asturias, establishing the first Christian monarchy in the region. His reign marked the beginning of the Reconquista, a centuries-long campaign to reclaim the Iberian Peninsula from Moorish rule.

In the 11th century, Alfonso VI (1040-1109), known as "The Brave," became the first King of Castile and León, uniting the two powerful kingdoms. His reign saw significant territorial gains against the Moors and the establishment of a code of laws known as the Fuero Juzgo.

The name Alfonso also has religious ties, as it was borne by several Catholic saints, including Alfonso Maria de' Liguori (1696-1787), a renowned theologian and founder of the Redemptorist religious order, who was canonized in 1839.

Among other notable figures, Alfonso X (1221-1284), known as "The Wise," was a prolific ruler of Castile and León, renowned for his patronage of literature, science, and the arts. He oversaw the creation of the Alfonsine Tables, a groundbreaking work in astronomy and navigation.

In the 15th century, Alfonso V (1396-1458), also known as "The Magnanimous," ruled as the King of Aragon, Naples, and Sicily. He was a significant patron of the arts and humanism during the Italian Renaissance.

Throughout history, the name Alfonso has been associated with various rulers, intellectuals, and religious figures, reflecting its enduring presence in the Iberian Peninsula and its cultural significance.