From the longer Wikipedia page , which also contains a family tree.
Jasper Tudor, 1st Duke of Bedford, 1st Earl of Pembroke, KG (Welsh: Siasbar Tudur) (c. 1431 – 21/26 December 1495) was the uncle of King Henry VII of England and the architect of his successful conquest of England and Wales in 1485. He was from the noble Tudor family of Penmynydd, North Wales.
Jasper Tudor bore the arms of the kingdom, with the addition of a bordure azure with martlets or (that is, a blue border featuring golden martlets).
His elder brother Edmond was born at Much Hadham Palace in Hertfordshire around 1430. Jasper the second son was born at the Bishop of Ely’s manor at Hatfield in Hertfordshire around 1431. There seemed to be a third son, Jasper's younger brother referred to as either Edward, Thomas or most likely Owen Tudor. Owen was born at Westminster Abbey in 1432, when the Dowager Queen was visiting her son Henry VI, her water broke prematurely and she was forced to seek the help of the monks at Westminster Abbey. Owen was taken from her and raised by the monks and according to his nephew Henry VII's personal historian Polydore Vergil the child was raised as a monk by the name Edward Bridgewater where he lived until his death in 1502. There is mention of a daughter who became a nun by Vergil but nothing is known of her. Jasper's mother's last child would be born in 1437 mere days before Catherine's own untimely death.
In 1436 when Jasper was about five years of age his mother Catherine of Valois once again was expecting another child, however she realised that she was dying from an illness, probably cancer, and sought the help of Bermondsey Abbey to be nursed by the sisters there. By 1 January she had written a will and had given birth to a short lived daughter, possibly named Margaret. On 3 January she died. After her death her husband Owen was arrested. It seems likely that while Catherine had been alive, the regency of Henry VI were reluctant to arrest Owen while the Queen could still protect him. The regents had made it illegal for anyone to marry the widowed queen without their permission, and since Owen was below her in rank, there had been no hope permission would be granted. Owen was sent to Newgate prison. Owen's children Edmund and Jasper, and possibly their unknown sister, were given to Catherine de la Pole who was a nun at Barking Abbey in Essex. She was the sister of William de la Pole, 1st Duke of Suffolk, a great favourite of Henry VI. Catherine de la Pole was to provide Owen Tudor's children with food, clothing, and lodging, and both boys were allowed servants to wait upon them as the King’s half-brothers.
Owen Tudor was released from prison, most likely thanks to his stepson Henry VI who, after providing for his stepfather, also provided for his two half-brothers who had become very dear to him. It is not clear whether Henry VI had known the existence of his half-brothers until his mother told him while she was dying in Bermondsey Abbey. After her death, Henry would take care of them and eventually raise them to the peerage. In turn they gave him unwavering loyalty and fought and promoted his and his Lancastrian family’s interests to the best of their ability. Sometime after March 1442, the young Jasper and his elder brother were brought from Barking Abbey to live at court. Henry arranged for the best priest to educate them not just in their academic studies, but on how to live a moral life. Most likely they also received military training, as when they grew up they were given military positions.
Although there was uncertainty as to whether Jasper and his two (or three) siblings were legitimate, their parents' probably secret marriage not being recognised by the authorities, he enjoyed all the privileges appropriate to his birth, including being invested as a Knight of the Garter. But on the accession of the Yorkist King Edward IV in 1461 he was subject to an attainder for supporting his Lancastrian half-brother, the deposed king Henry, to whom Jasper was a tower of strength. He strove to place his half-nephew Prince Edward of Lancaster on the throne and provided absolute loyalty to his royal half-brother and Margaret of Anjou, his half-brother's wife. Jasper would also help his other sister-in-law Lady Margaret Beaufort, Countess of Richmond and Derby to enable her son Henry Tudor win the throne in 1485 as King Henry VII, father of King Henry the VIII.
Jasper was an adventurer whose military expertise, some of it gained in the early stages of the Wars of the Roses, was considerable, notwithstanding that the only major battle he had taken part in was Mortimer's Cross in February 1461, where he lost the battle to the future Edward IV, and his father Owen to the executioner's axe. He remained in touch with Margaret of Anjou, Queen of Henry VI, as she struggled to regain her son's inheritance, and he held Denbigh Castle for the House of Lancaster.
Jasper also brought up his nephew, Henry Tudor, whose father had died before his birth, until 1461 when he lost Pembroke Castle to William Herbert. After being welcomed by Louis XI of France the following year, he returned to North Wales in 1468 only to be defeated by Herbert.
He briefly regained the earldom of Pembroke a couple of years later but following the return of the Yorkist king Edward IV from temporary exile in 1471, he fled again onto the continent. Escaping from Tenby with Henry, storms in the English Channel forced them to land at Le Conquet in Brittany where they sought refuge from Duke Francis II. Although Edward placed diplomatic pressure on the Duke of Brittany, the uncle and nephew remained safe from the clutches of the English king who died in April 1483.
It was thanks to Jasper that Henry acquired the tactical awareness that made it possible for him to defeat the far more experienced Richard III at the Battle of Bosworth Field in 1485. On Henry's subsequent accession to the throne as Henry VII, Jasper was restored to all his former titles, including Knight of the Garter, and made Duke of Bedford. In 1488, he took possession of Cardiff Castle.
Catherine was the daughter of Richard Woodville, 1st Earl Rivers and Jacquetta of Luxembourg, and thus was sister to (among others) Edward IV's queen Elizabeth Woodville, Anthony Woodville, 2nd Earl Rivers and Richard Woodville, 3rd Earl Rivers. She was also the widow of Henry Stafford, 2nd Duke of Buckingham.
They may have had one stillborn son c. 1490. Catherine survived Jasper and later married Sir Richard Wingfield of Kimbolton Castle.
Helen Tudor (by Mevanvy or Myvanwy ferch N (b. Wales, d. bef. 1485), born c. 1459), wife of a skinner William Gardiner, of London, sometimes spelled William Gardynyr (born c. 1450), having by him: Thomas Gardiner, Prior of Tynemouth and four daughters, Philippa, Margaret, Beatrice and Anne. After her husband's death she married William Sybson. 19th century genealogists mistakenly conflated Thomas Gardiner with Stephen Gardiner, bishop of Winchester.
Joan Tudor, wife of William ap Yevan (son of Yevan Williams and Margaret Kemoys), and reported mother of Morgan ap William (or Williams) (born Llanishen, Glamorganshire, Wales, 1479), later married at Putney Church, Norwell, Nottinghamshire, in 1499 to Catherine or Katherine Cromwell, born Putney, London, c. 1483, an older sister of Tudor statesman Thomas Cromwell, 1st Earl of Essex. They were fourth-generation ancestors to Oliver Cromwell, meaning Oliver Cromwell was a descendant of the Welsh Royal Family, via Joan Tudor's grandfather, Owen Tudor.
He died on 21 or 26 December 1495, and was buried at Keynsham Abbey in Somerset which Lady Agnes Cheyne, the incumbent of Chenies Manor House, bequeathed to him in 1494.