Royalty who died as children

Isabel Stuart (28 August 1676 – 2 March 1681), also called Isobel and Isabella, was a daughter of the future King James II of England and his second wife, Mary of Modena.
Isabel was born at St James's Palace in London. She was the second daughter of James and Mary, after her sister Catherine Laura who died eleven months before Isabel's birth. Isabel had two older half-sisters from her father's first marriage to Anne Hyde: Mary and Anne; both would become reigning Queens of England. Isabel's paternal grandparents were Charles I of England and his wife Henrietta Maria of France, her maternal grandparents were Alfonso IV d'Este and Laura Martinozzi.

Edgar Stuart, Duke of Cambridge (14 September 1667 – 8 June 1671) was the fourth son of James, Duke of York (later James II of England) and his first wife Anne Hyde. He was second in the line of succession to the English and Scottish thrones.

Charles Stuart, Duke of Kendal (4 July 1666 – 22 May 1667) was the third son of James, Duke of York (later James II of England) and his first wife Anne Hyde.
Charles was born on 4 July 1666 at St James's Palace. His godparents were his three-year-old brother James, Duke of Cambridge, his cousin James, Duke of Monmouth, and Emilia von Nassau, Countess of Ossory. He was designated Duke of Kendal and was to have been created Duke of Kendal, Earl of Wigmore, and Baron of Holdenby, but no patent was ever enrolled. He died at St James's Palace at the age of 10 months on 22 May 1667 and was buried in Westminster Abbey on 30 May 1667.

Monsieur d'Orléans (16 April 1607 – 17 November 1611) was the second son and fourth child of Henry IV of France and his consort, Marie de' Medici. Commonly ascribed the names Nicolas or Nicolas Henri and the title Duke of Orléans, he was neither baptised nor invested as such during the course of his short life.
He was betrothed to Marie de Bourbon-Montpensier, heiress to vast lands of the extended House of Bourbon. After his father's death in 1610, he was heir presumptive to his older brother, Louis XIII. Of frail health, he died of seizures brought on by hydrocephalus at the age of four, whereupon his title and betrothal were transferred to Gaston, his younger brother.

Henry, Duke of Cornwall (1 January 1511 – 22 February 1511) was the first living child of King Henry VIII of England and his first wife, Catherine of Aragon, and though his birth was celebrated as that of the heir apparent, he died within weeks. His death and the failure of Henry VIII and Catherine to produce another surviving male heir led to succession and marriage crises that affected the relationship between the English church and Roman Catholicism, giving rise to the English Reformation.

Edmund Tudor, Duke of Somerset (21 February 1499 – 19 June 1500) was an English prince, and the sixth child of King Henry VII of England and his wife, Elizabeth of York.
He was styled from birth Duke of Somerset, but never formally created a peer.