British kings and queens are famous today. But many heirs to the British throne never became the actual king or queen due to various quirks of fate. This is their story. The stories include the oldest son of William the Conqueror, who lost the chance to become king because he was off fighting in the First Crusade; the White Ship disaster of 1120, England's medieval Titanic, in which the sole male heir to the throne, and many others, drowned; an intrepid woman who nearly became queen in her own right four centuries before a woman actually did so; two princes who should have become a second King Arthur; the romantic warrior known to history as the Black Prince; the Princes in the Tower, who were supposedly murdered by King Richard III; the ill-fated Mary, Queen of Scots, beheaded by Queen Elizabeth I after an utterly unfair trial; James, who was born the heir and then was overthrown while still a baby, and was later known as the Old Pretender; a beloved Nineteenth Century princess who tragically died in childbirth at the age of 21; and many more. Who suspected that the heirs who never reigned are every bit as interesting as those who did reign?