Title: Cosimo I de' Medici, Grand Duke of Tuscany
Content:  Cosimo I de' Medici (12 June 1519 &ndash; 21 April 1574) was the second Duke of Florence from 1537 until 1569, when he became the first Grand Duke of Tuscany, a title he held until his death.
Title: Cosimo II de' Medici, Grand Duke of Tuscany
Content:  Cosimo II de' Medici (12 May 1590 &ndash; 28 February 1621) was Grand Duke of Tuscany from 1609 until his death. He was the elder son of Ferdinando I de' Medici, Grand Duke of Tuscany, and Christina of Lorraine. For the majority of his twelve-year reign, he delegated the administration of Tuscany to his ministers. He is best remembered as the patron of Galileo Galilei, his childhood tutor.
Title: Cosimo I de' Medici, Grand Duke of Tuscany
Content:  Cosimo was born in Florence on 12 June 1519, the son of the famous condottiere Ludovico de' Medici (known as Giovanni delle Bande Nere) and his wife Maria Salviati, herself a granddaughter of Lorenzo the Magnificent. He was the grandson of Caterina Sforza, the Countess of Forlì and Lady of Imola. Cosimo came to power in 1537 at age 17, just after the 26-year-old Duke of Florence, Alessandro de' Medici, was assassinated. Cosimo was from a different branch of the Medici family, descended from Giovanni il Popolano, the great-grandson of Giovanni di Bicci de' Medici, founder of the Medici Bank. It was necessary to search 
Title: Cosimo I de' Medici, Grand Duke of Tuscany
Content:  a successor outside of the "senior" branch of the Medici family descended from Cosimo di Giovanni de' Medici, since the only male child of Alessandro, the last lineal descendant of the senior branch, was born out-of-wedlock and was only four years' old at the time of his father's death. Up to the time of his accession, Cosimo had lived only in Mugello (the ancestral homeland of the Medici family) and was almost unknown in Florence. However, many of the influential men in the city favoured him as the new duke. Several hoped to rule through him, thereby enriching themselves at the state's expense. However, as 
Title: Cosimo III de' Medici, Grand Duke of Tuscany
Content:  Cosimo III de' Medici (14 August 1642 – 31 October 1723 ) was Grand Duke of Tuscany from 1670 until his death in 1723, the sixth and penultime from the House of Medici. He reigned from 1670 to 1723, and was the elder son of Grand Duke Ferdinando II. Cosimo's 53-year-long reign, the longest in Tuscan history, was marked by a series of laws that regulated prostitution and May celebrations. His reign also witnessed Tuscany's deterioration to previously unknown economic lows. He was succeeded by his elder surviving son, Gian Gastone, when he died, in 1723. He married Marguerite Louise d'Orléans, a cousin of Louis XIV. The marriage was solemnized by proxy in the King's Chapel at 
Title: Cosimo III de' Medici, Grand Duke of Tuscany
Content:  Cosimo de' Medici was born on 14 August 1642, the eldest surviving son of Vittoria della Rovere of Urbino, and Ferdinando II de' Medici, Grand Duke of Tuscany. Their previous two children had died shortly after birth. Grand Duke Ferdinando wished to give his son the finest scientific education available, but the pious Grand Duchess Vittoria opposed. The latter got her way. Volunnio Bandinelli, a Sienese theologian, was appointed Cosimo's tutor. His character was analogous to the Grand Duchess's. As a youth, Cosimo revelled in sports. His uncle Gian Carlo once wrote to another family member with "news that should surprise you....The young prince [Cosimo] has killed a goose in mid-air." Cosimo, at the age of 11, killed five pigs with five shots. The Luchese Ambassador praised the young Cosimo to the skies. His successor, however, noticed a somewhat different person, whom he described as "melancholy." By 1659, Cosimo had ceased smiling in public. He frequently visited places of religious worship and surrounded himself with friars and priests, concerning Grand Duke Ferdinando. Cosimo's only sibling, Francesco Maria de' Medici, the fruit of his parents' brief reconciliation, was born the next year.
Title: Francesco I de' Medici, Grand Duke of Tuscany
Content:  Born in Florence, he was the son of Cosimo I de' Medici, Grand Duke of Tuscany, and Eleanor of Toledo. He served as regent for his father Cosimo after he retired from his governing duties in 1564.
Title: Ferdinando II de' Medici, Grand Duke of Tuscany
Content:  Ferdinando II de' Medici (14 July 1610 &ndash; 23 May 1670) was grand duke of Tuscany from 1621 to 1670. He was the eldest son of Cosimo II de' Medici and Maria Maddalena of Austria. He was remembered by his contemporaries as a man of culture and science, actively participating in the Accademia del Cimento, the first scientific society in Italy, formed by his younger brother, Leopoldo de' Medici. His 49-year rule was punctuated by the beginning of Tuscany's long economic decline, which was further exacerbated by his successor, Cosimo III de' Medici. He married Vittoria della Rovere, a first cousin, with whom he had two children who reached adulthood: the aforementioned Cosimo III, and Francesco Maria de' Medici, Duke of Rovere and Montefeltro, a cardinal.
Title: Cosimo II de' Medici, Grand Duke of Tuscany
Content: (see index, v.1, for information on Cosimo as a patron of the arts) 
Title: House of Medici
Content:  Another outstanding figure of the 16th-century Medici family was Cosimo I, who rose from relatively modest beginnings in the Mugello to attain supremacy over the whole of Tuscany. Against the opposition of Catherine de' Medici, Paul III and their allies, he prevailed in various battles to conquer Florence's hated rival Siena and found the Grand Duchy of Tuscany. Cosimo purchased a portion of the island of Elba from the Republic of Genoa and based the Tuscan navy there. He died in 1574, succeeded by his eldest surviving son Francesco, whose death without male heirs led to the succession of his younger brother, Ferdinando, in 1587. 

Question: Who is the father of Cosimo I de' Medici, Grand Duke of Tuscany?
Answer: Giovanni delle Bande Nere.
Giovanni de Medici.