Descended from Owen Tudor, properly Owain ap Mareddud ap Tudur, born around 1400 in the Anglesey area of Wales. At some point, in his 20s, having become attached to the English royal court of Henry V, he came into contact with Henry's widow, the dowager-Queen, Catherine of Valois. She, it is said, formed a passion for him when she was refused permission to marry Edmund Beaufort. By 1428 they were, it appears, married (albeit secretly) -- in that year an Act was passed prohibiting secret marriages with dowager Queens, which argues that the event had already occurred.
Their eldest son, Edmund (later Earl of Richmond) was born in 1430, followed by Jasper a year later, who would become Earl of Pembroke and Duke of Bedford.
In 1436 the Queen's children were taken from her and she was confined (possibly because of ill-health, possibly for reasons of state) to the abbey at Bermondsey. There she died in January 1437 and Owain was summoned before Henry VI. Despite being acquitted of all charges against him, and despite being given a safe-conduct by the King, he was taken and imprisoned. Later he was released from custody and pardoned. He elected to "retire" to Wales, but became an ardent Lancastrian and was granted an annunity. He was made Henry's Keeper of the Parks at Denbigh, but was captured at the Battle of Mortimer's Cross in 1461 and was executed on the orders of Edward IV.
By then Edmund was married, to the teenage heiress Margaret Beaumont, and she bore his son Henry, although the boy was born after his father had died. Henry, in due course, took the English throne, as Henry VII, marrying Elizabeth Plantagenet, daughter of Edward IV, and having a son Henry by her, Henry VIII.