The queen of Castile, Joanna of Castile, married this member of the house of Habsburg who was the son of which monarch?
Philip I of Castile Philip I (22 July 1478 – 25 September 1506) called the Handsome or the Fair, was the first member of the house of Habsburg to be King of Castile. The son of Holy Roman Emperor Maximilian I, at the age of three Philip inherited the greater part of the Duchy of Burgundy and the Burgundian Netherlands (as Philip IV) from his mother, Mary, and at 27 briefly succeeded to the Crown of Castile as the husband of Queen Joanna, who was also heir presumptive to the Crown of Aragon. He was the first Habsburg monarch in Spain. He never inherited his father's territories or became Holy Roman Emperor because he predeceased his father, but his son Emperor Charles V eventually united the Habsburg, Burgundian, Castilian, and Aragonese inheritances.
Count Leo Stefan of Habsburg Count Leo Stefan Maria Carl Wolfgang Rudolf von Fidelis of Habsburg (born June 12, 1928 in Żywiec) is a morganaut of the House of Habsburg-Lorraine and the representative of the Teschen ducal line. He is the son of Archduke Leo Karl (1893–1939) and Countess Maria-Klothilde de Thuillières von Montjoye-Vaufrey et de la Roche (1893–1978) and a grandson of Archduke Charles Stephen of Austria. He is today the heir to the Dukedom of Teschen. because of the unequal marriage of his parents. He thus is only entitled to use the title Count of Habsburg. He has seven children of whom Count Albrecht of Habsburg (born 1963), who is his heir to the Dukedom.