– 1438 besieging Naples, Italy), Viceroy of Sicily (1424–1425) and Duke of Noto, was the sixth child of King Ferdinand I of Aragón and Countess Eleanor of Alburquerque.
The brothers future king John, Henry and Peter formed an ambitious group of princes, known as the Infantes of Aragon, who aimed to seize power in Castile at the expense of their cousin and brother in law, King Juan II of Castile.
They were particularly opposed to Álvaro de Luna, favourite of the king and central figure of the Castilian Kingdom.
His capture in 1431 led to the pacification of the regions of Salamanca and Extremadura, as he was required to surrender all the fortresses and possessions that his family owned there in order to be released.
It is not clear how or if Alfonso responded to this letter, although in a letter that reached Yeshaq's successor Zara Yaqob in 1450, Alfonso wrote that he would be happy to send artisans to Ethiopia if their safe arrival could be guaranteed, for on a previous occasion a party of thirteen of his subjects traveling to Ethiopia had all perished.