Calixtus III, also known as Alfonso de Borja, was a 15th century Spanish Pope who served for only three years between 1455 and 1458. He was succeeded by Pope Pius II after his sudden death, and his legacy lives on through his numerous contributions to the Catholic Church. According to historical records and religious texts, some of the synonyms used to refer to Calixtus III include Pope Alfonso, Alonzo, Borgia, and Borja. These names are interchangeably used to describe the prominent religious figure who played a significant role in the expansion of the Church during his short but memorable reign as Pope.