Isabella of Castile

Born April 22, 1451, she was the eldest child of King Juan II and his second wife Isabel of Portugal. Unfortunately for the young Isabella, after the sudden death of her father, her mother became increasingly depressed and mad. Her older half brother Henry became then became king and married Juana, the sister of the King of Portugal who had a daughter, also named Juana, that many believed was actually the daughter of Henry's chief steward. The girl would proclaim her right to the throne the rest of her life. During Henry's reign, divisive support between him and their younger brother Alfonso among the country's most powerful nobles put Isabella in the middle, and she was used as a pawn to check Alfonso and his supporters until he died of an illness in 1468. In 1469, she married Ferdinand of Aragon, much to her brother's displeasure, nonetheless, Isabella was then made the heir, and on Henry's death in 1474, she became Queen of Castilla and Leon. The couple ruled jointly and had five children: Isabel (who died in childbirth in 1498), Juan (who died of illness in 1497), Juana (better known as Juana la Loca, who became queen in 1504 and whose son Charles became Holy Roman Emperor), Maria (whose son became the King of Portugal), and Catalina (she, of course, became Catherine of Aragon and was the first wife of Henry VIII). Isabella is also well remembered for funding the infamous trip of Christopher Columbus in 1492, and as one of the "Catholic Monarchs" due to her and her husband driving the Jews and Moors out of Spain, and, less favorably, the Inquisition. Still, she is remembered today as both a remarkable woman and remarkable queen. Here's some novels on her I found worth checking out:

Isabella is barely a teenager when she becomes an unwitting pawn in a plot to dethrone her half brother, King Enrique. Suspected of treason and held captive, she treads a perilous path, torn between loyalties, until at age seventeen she suddenly finds herself heiress of Castile, the largest kingdom in Spain. Plunged into a deadly conflict to secure her crown, she is determined to wed the one man she loves yet who is forbidden to her—Fernando, prince of Aragón. As they unite their two realms under “one crown, one country, one faith,” Isabella and Fernando face an impoverished Spain beset by enemies. With the future of her throne at stake, Isabella resists the zealous demands of the inquisitor Torquemada even as she is seduced by the dreams of an enigmatic navigator named Columbus. But when the Moors of the southern domain of Granada declare war, a violent, treacherous battle against an ancient adversary erupts, one that will test all of Isabella’s resolve, her courage, and her tenacious belief in her destiny.

Isabella of Spain was a great woman, a great Queen. Crown Of Aloes is presented as a personal chronicle. Within the framework of known fact and detail drawn from hitherto unexploited contemporary Spanish sources, a novelist's imagination and understanding have provided motives, thoughts, and private conversations, helping to build up the fascinating character Isabella must have been. Her fortunes were varied indeed: she knew acute poverty, faced anxiety and danger with high courage, gave much, suffered much, lived to the full. At the end she was mainly aware of her failures. It was left to others to realise how spectacular her successes had been.

Married to Ferdinand after continual fears and disappointments, Isabella triumphed over every danger, convinced of her true destiny. With the might of Portugal humbled, the Court of the Sovereigns saw the rise of Torquemada, the establishment of the dreaded Inquisition, and the coming of Columbus, who left the woman he loved to make a dream reality. Ambitious and unfaithful, Ferdinand longed to lead his troops against the Moorish strongholds. Isabella knew a united Spain and a glorious future could be theirs, but they must only share it together.

Two I found on Juana:

Juana of Castile, third child of the Spanish monarchs Isabel and Fernando, grows up with no hope of inheriting her parents’ crowns, but as a princess knows her duty: to further her family’s ambitions through marriage. When she weds the Duke of Burgundy, a young man so beautiful that he is known as Philippe the Handsome, she dares to hope that she might have both love and crowns. He is caring, charming, and attracted to her—seemingly a perfect husband.
But when Queen Isabel dies, the crowns of Spain unexpectedly pass down to Juana, leaving her husband and her father hungering for the throne. Rumors fly that the young Queen has gone mad, driven insane by possessiveness. Locked away in a palace and unseen by her people for the next forty-six years, Juana of Castile begins one of the most controversial reigns in Spanish history, one that earned her the title of Juana the Mad.

Born amid her parents’ ruthless struggle to unify and strengthen their kingdom, Juana, at the age of sixteen, is sent to wed Philip, heir to the Habsburg Empire. Juana finds unexpected love and passion with her dashing young husband, and at first she is content with her children and her married life. But when tragedy strikes and she becomes heir to the Spanish throne, Juana finds herself plunged into a battle for power against her husband that grows to involve the major monarchs of Europe. Besieged by foes on all sides, Juana vows to secure her crown and save Spain from ruin, even if it costs her everything. (all via Amazon)

Royal Blood podcast, episode 40

Happy Reading!