For further distiction, Mary I of England was the daughter of Catalina de Aragón, the Spanish Pricess who was the 1st wife to Henry VIII. So Mary I was also aunt of her own husband, who was the grandson of her aunt Queen Juana 'La Loca', her mother's eldest sister, and both descend from Queen Isabel de Castilla and King Fernando de Aragón.

I must admit my knowledge of royal genealogies (English, French and Spanish in particular) comes from historical novels, a fascinating subject but unfortunately not for practical use, evenless when I am Mexican :-S