Born at Greenwich Palace, Henry VIII was the third child of Henry VII and Elizabeth of York and their second son.[6] Of the young Henry's six siblings, only three — Arthur, Prince of Wales; Margaret; and Mary — survived infancy.[7] He was baptised by Richard Fox, the Bishop of Exeter, at a church of the Observant Franciscans close to the palace.[8] In 1493, at the age of two, Henry was appointed Constable of Dover Castle and Lord Warden of the Cinque Ports. He was subsequently appointed Earl Marshal of England and Lord Lieutenant of Ireland aged three, and was inducted into the Order of the Bath soon after. The day after the ceremony he was made Duke of York; a month or so later he was made Warden of the Scottish Marches. In May 1495, he was appointed to the Order of the Garter.[8] Henry was given a first-rate education from leading tutors, becoming fluent in Latin, French, and at least some Spanish and Ancient Greek.[9][10] As it was expected that the throne would pass to Prince Arthur, Henry's older brother, Henry was prepared for a clerical career. Elizabeth of York, his mother, died when Henry was aged 11.[9] Not much is known about his early life – save for his appointments – because he was not expected to become king.[8] Due to the young Henry's infancy, most of his duties were carried out by others; at age five, however, he witnessed the signing of a royal grant in what is believed to be his first official act as Duke. In November 1501, Henry also played a considerable part in the ceremonies surrounding the marriage of his brother, Prince Arthur, to Catherine of Aragon.[11] In 1502, Arthur died at the age of 15, after only 20 weeks of marriage to Catherine of Aragon.[12] Arthur's death thrust all his duties upon his younger brother, the 10-year-old Henry, who after a little debate succeeded him to the Dukedom of Cornwall in October 1502, and the Prince of Wales and Earl of Chester in February 1503.[13] Henry VII appears to have given his son few tasks during his lifetime, perhaps weary of the death of his first son after sending him to attend to his princely duties in Wales. It is believed that the young Henry was strictly supervised (although to quite what extent is unclear, given that he spent much time in sports) and did not appear in public.[14] Henry VII renewed his efforts to seal a marital alliance between England and Spain, by offering his second son in marriage to Catherine, youngest surviving child of King Ferdinand II of Aragon and Queen Isabella I of Castile.[12] Both Isabella and Henry VII were keen on the idea, which had arisen very shortly after Arthur's death.[15] On 23 June 1503, a treaty was signed for their marriage, and they were betrothed two days later.[16] A papal dispensation was only needed for the "impedement of public honesty" if the marriage had not been consummated as Catherine and her duenna claimed, but Henry VII and the Spanish Ambassador set out to obtain a dispensation for "affinity", which took account of consummation.[16] The young Henry's age, only eleven, prevented cohabitation and the parties were thus required to wait.[15] Isabella's death in 1504, and the ensuing problems of succession in Castile, changed Catherine's position. Her father, Ferdinand, preferred her to stay in England, but Henry VII's relations with Ferdinand had deteriorated.[17] Catherine was left in limbo for some time, culminating in Prince Henry's rejection of the marriage as soon he was able, at the age of 14. Ferdinand's solution was to make his daughter ambassador, allowing her to stay. Devout, she began to believe that it was God's will that she marry the prince.[18]

In the winter of 1532, Henry attended a meeting with Francis I of France at Calais in which he enlisted the support of the French king for his new marriage.[62] Immediately upon returning to Dover in England, Henry and Anne went through a secret wedding service.[63] She soon became pregnant and there was a second wedding service in London on 25 January 1533. On 23 May 1533, Cranmer, sitting in judgment at a special court convened at Dunstable Priory to rule on the validity of the king's marriage to Catherine of Aragon, declared the marriage of Henry and Catherine null and void. Five days later, on 28 May 1533, Cranmer declared the marriage of Henry and Anne to be valid.[64] Catherine was formally stripped of her title as queen, and Anne was crowned queen consort on 1 June 1533. The queen gave birth to a daughter slightly prematurely on 7 September 1533. The child was christened Elizabeth, in honour of Henry's mother, Elizabeth of York.[65] Rejecting the decisions of the Pope, Parliament validated the marriage of Henry and Anne with the First Succession Act (Act of Succession 1533). Catherine's daughter, Mary, was declared illegitimate, and Anne's issue were declared next in the line of succession. Most notable in this declaration was a clause repudiating "any foreign authority, prince or potentate". All adults in the Kingdom were required to acknowledge the Act's provisions by oath; those who refused were subject to imprisonment for life. Any publisher or printer of any literature alleging that the marriage was invalid was automatically guilty of high treason and could be punished by death.

The day after Anne's execution in 1536 Henry became engaged to Seymour, who was one of the Queen's ladies-in-waiting.[77] They were married 10 days later. Henry granted his assent to the Laws in Wales Act 1535, which legally annexed Wales, uniting England and Wales into one unified nation. This was followed by the Second Succession Act (Act of Succession 1536), which declared Henry's children by Queen Jane to be next in the line of succession and declared both the Lady Mary and the Lady Elizabeth illegitimate, thus excluding them from the throne. The king was granted the power to further determine the line of succession in his will, should he have no further issue.[78] On 12 October 1537, Jane gave birth to a son, Prince Edward, the future Edward VI.[79] The birth was difficult and the queen died on 24 October 1537 from an infection and was buried in Windsor.[80] Measures were immediately put in place to find another wife for Henry, which, at the insistence of Cromwell and the court, were focused on the Continent.[81] After Jane's death, the entire court mourned with Henry for an extended period. Henry considered Jane to be his "true" wife, being the only one who had given him the male heir that he so desperately sought. He was buried next to her.

At this time, Henry wished to marry once again to ensure the succession. Cromwell, now Earl of Essex, suggested Anne, the sister of the Duke of Cleves, who was seen as an important ally in case of a Roman Catholic attack on England, for the duke fell between Lutheranism and Catholicism.[90] Hans Holbein the Younger was dispatched to Cleves to paint a portrait of Anne for the king.[91] Despite speculation that Holbein painted her in an overly flattering light, it is more likely that the portrait was accurate; Holbein remained in favour at court.[92] After regarding Holbein's portrayal, and urged by the complimentary description of Anne given by his courtiers, the king agreed to wed Anne.[93] On Anne's arrival in England, Henry is said to have found her unattractive, privately calling her a "Flanders Mare".[94] Henry wished to annul the marriage so he could marry another.[95] The Duke of Cleves had become engaged in a dispute with the Holy Roman Emperor, with whom Henry had no desire to quarrel.[citation needed] Anne did not argue, and confirmed that the marriage had never been consummated.[96] Henry was said to have come into the room each night and merely kissed his new bride on the forehead before retiring.[citation needed] The subject of Anne's previous marriage arrangements with the Duke of Lorraine's son eventually provided for the answer, one complicated enough that the remaining impediments to an annulment were thus removed.[97] The marriage was subsequently dissolved and Anne received the title of "The King's Sister", two houses and a generous allowance.[96] Cromwell, meanwhile, fell out of favour although it is unclear exactly why, for there is little evidence of differences of domestic or foreign policy; despite his role, he was not officially accused of being responsible for Henry's failed marriage. He was subsequently attainted and beheaded.[98] Cromwell had been amongst enemies at court and the failure of the marriage to Anne allowed Cromwell's greatest rival, the Duke of Norfolk, to offer up his niece – Catherine Howard to the king. Charges of treason, selling export licences, granting passports, and drawing up commissions without permission were all laid at Cromwell's table, and may have been accompanied with blame for the Cleves failure, and the failure of the foreign policy it accompanied.[99] The office of Vicegerent in Spirituals, which had been specifically created for him, was not filled.[citation needed] Shortly after, the religious reformers Robert Barnes, William Jerome and Thomas Garret were burned as heretics, innocent of the crime attributed to them.[100]

On 28 July 1540 (the same day Cromwell was executed), Henry married the young Catherine Howard, Anne Boleyn's first cousin and a lady-in-waiting of Anne's.[101] He was absolutely delighted with his new queen, and awarded her the lands of Cromwell and a vast array of jewellery.[102] Soon after her marriage, however, Queen Catherine had an affair with the courtier Thomas Culpeper. She employed Francis Dereham, who was previously informally engaged to her and had an affair with her prior to her marriage, as her secretary. The court was informed of her affair with Dereham whilst Henry was away; they dispatched Thomas Cranmer to investigate, who brought evidence of Queen Catherine's previous affair with Dereham to the king's notice.[103] Though Henry originally refused to believe the allegations, Dereham confessed. It took another meeting of the council, however, before Henry believed and went into a rage, blaming the council before consoling himself in hunting.[104] When questioned, the queen could have admitted a prior contract to marry Dereham, which would have made her subsequent marriage to Henry invalid, but she instead claimed that Dereham had forced her to enter into an adulterous relationship. Dereham, meanwhile, exposed Queen Catherine's relationship with Thomas Culpeper. Culpeper and Dereham were executed, and Catherine joined them on 13 February 1542.[105] In 1540, Henry sanctioned the destruction of shrines to saints. In 1542, England's remaining monasteries were all dissolved, and their property transferred to the Crown. Abbots and priors lost their seats in the House of Lords; only archbishops and bishops came to comprise the ecclesiastical element of the body. The Lords Spiritual, as members of the clergy with seats in the House of Lords were known, were for the first time outnumbered by the Lords Temporal.

Late in life, Henry became obese (with a waist measurement of 54 inches/137 cm) and had to be moved about with the help of mechanical inventions. He was covered with painful, pus-filled boils and possibly suffered from gout. His obesity and other medical problems can be traced from the jousting accident in 1536, in which he suffered a leg wound. The accident actually re-opened and aggravated a previous leg wound he had sustained years earlier, to the extent that his doctors found it difficult to treat it. The wound festered for the remainder of his life and became ulcerated, thus preventing him from maintaining the same level of physical activity he had previously enjoyed. The jousting accident is believed to have caused Henry's mood swings, which may have had a dramatic effect on his personality and temperament.[108] The theory that Henry suffered from syphilis has been dismissed by most serious historians.[109] A more recent and credible theory suggests that Henry's medical symptoms, and those of his older sister Margaret Tudor, are characteristic of untreated Type II diabetes. According to research published in March 2011, his wives' pattern of pregnancies and his mental deterioration suggests that the king may have been Kell positive and suffered from McLeod syndrome.[110] Obesity specialists at Imperial College London have analysed Henry VIII’s history and body morphology to identify that this was likely as a result of traumatic brain injury after his 1536 jousting accident, which in turn led to a neuroendocrine cause of his obesity. This analysis identifies growth hormone deficiency (GHD) as the source for his increased adiposity but also significant behavioural changes (multiple marriages and war with France) noted in his later years.[111] Henry's obesity hastened his death at the age of 55, which occurred on 28 January 1547 in the Palace of Whitehall, on what would have been his father's 90th birthday. He died soon after allegedly uttering his last words: "Monks! Monks! Monks!",[112] perhaps in reference to the monks he caused to be evicted during the dissolution of the monasteries.[113] Henry VIII was interred in St George's Chapel in Windsor Castle, next to his wife Jane Seymour.[114] Over a hundred years later, Charles I was buried in the same vault. After his death, his only legitimate son, Edward, inherited the Crown, becoming Edward VI. Since Edward was only nine years old at the time, he could not exercise actual power. Henry's will designated 16 executors to serve on a council of regency until Edward reached the age of 18. The executors chose Edward Seymour, 1st Earl of Hertford, Jane Seymour's elder brother, to be Lord Protector of the Realm. In default of heirs to Edward, the throne was to pass to Henry VIII's daughter by Catherine of Aragon, the Princess Mary, and her heirs. If Mary's issue failed, the crown was to go to Henry's daughter by Anne Boleyn, Princess Elizabeth, and her heirs. Finally, if Elizabeth's line became extinct, the crown was to be inherited by the descendants of Henry VIII's deceased younger sister, Mary. The descendants of Henry's sister Margaret Tudor – the royal family of Scotland – were therefore excluded from succession according to this act. This final provision failed when James VI of Scotland subsequently became James I of England upon Elizabeth's death.