Edward II (25 April 1284 – 21 September 1327), also known as Edward of Caernarfon or Caernarvon, was King of England from 1307 until he was deposed in January 1327. The fourth son of Edward I, Edward became the heir to the throne following the death of his older brother Alphonso. Beginning in 1300, Edward accompanied his father on campaigns in Scotland, and in 1306 he was knighted in a grand ceremony at Westminster Abbey. Edward succeeded to the throne the next year, following his father's death. In 1308, he married Isabella, daughter of the powerful King Philip IV of France, as part of a long-running effort to resolve the tensions between the English and French crowns.

Edward had a close and controversial relationship with Piers Gaveston, who had joined his household in 1300. The precise nature of Edward and Gaveston's relationship is uncertain; they may have been friends, lovers, or sworn brothers. Gaveston's arrogance and power as Edward's favourite provoked discontent both among the barons and the French royal family, and Edward was forced to exile him. On Gaveston's return, the barons pressured the King into agreeing to wide-ranging reforms called the Ordinances of 1311. The newly empowered barons banished Gaveston, to which Edward responded by revoking the reforms and recalling his favourite. Led by Edward's cousin Thomas, 2nd Earl of Lancaster, a group of the barons seized and executed Gaveston in 1312, beginning several years of armed confrontation. English forces were pushed back in Scotland, where Edward was decisively defeated by Robert the Bruce at the Battle of Bannockburn in 1314. Widespread famine followed, and criticism of the King's reign mounted.

The Despenser family, in particular Hugh Despenser the Younger, became close friends and advisers to Edward, but in 1321 Lancaster and many of the barons seized the Despensers' lands and forced the King to exile them. In response, Edward led a short military campaign, capturing and executing Lancaster. Edward and the Despensers strengthened their grip on power, revoking the 1311 reforms, executing their enemies and confiscating estates. Unable to make progress in Scotland, Edward finally signed a truce with Robert. Opposition to the regime grew, and when Isabella was sent to France to negotiate a peace treaty in 1325, she turned against Edward and refused to return. Isabella allied herself with the exiled Roger Mortimer, and invaded England with a small army in 1326. Edward's regime collapsed and he fled into Wales, where he was captured in November. Edward was forced to relinquish his crown in January 1327 in favour of his son, Edward III of England, and he died in Berkeley Castle on 21 September, probably murdered on the orders of the new regime.

Edward's relationship with Gaveston inspired Christopher Marlowe's 1592 play Edward II, along with other plays, films, novels and media. Many of these have focused on the possible sexual relationship between the two men. Edward's contemporaries criticised his performance as a king, noting his failures in Scotland and the oppressive regime of his later years, although 19th-century academics have argued that the growth of parliamentary institutions during his reign was a positive development for England over the longer term. Debate has continued into the 21st century as to whether Edward was a lazy and incompetent king, or simply a reluctant and ultimately unsuccessful ruler.

Edward II was the fourth son of Edward I, King of England, Lord of Ireland, and ruler of Gascony in south-western France (which he held as the feudal vassal of the king of France), and Eleanor, Countess of Ponthieu in northern France. Eleanor was from the Castilian royal family. Edward I proved a successful military leader, leading the suppression of the baronial revolts in the 1260s and joining the Ninth Crusade. During the 1280s he conquered North Wales, removing the native Welsh princes from power and, in the 1290s, he intervened in Scotland's civil war, claiming suzerainty over the country. He was considered an extremely successful ruler by his contemporaries, largely able to control the powerful earls that formed the senior ranks of the English nobility. The historian Michael Prestwich describes Edward I as "a king to inspire fear and respect", while John Gillingham characterises him as an "efficient bully".

Despite Edward I's successes, when he died in 1307 he left a range of challenges for his son to resolve. One of the most critical was the problem of English rule in Scotland, where Edward I's long but ultimately inconclusive military campaign was ongoing when he died. His control of Gascony created tension with the French kings. They insisted that the English kings give homage to them for the lands; the English kings saw this demand as insulting to their honour, and the issue remained unresolved. Edward I also faced increasing opposition from his barons over the taxation and requisitions required to resource his wars, and left his son debts of around £200,000 on his death.

Edward II was born in Caernarfon Castle in north Wales on 25 April 1284, less than a year after Edward I had conquered the region, and as a result is sometimes called Edward of Caernarfon. The King probably chose the castle deliberately as the location for Edward's birth as it was an important symbolic location for the native Welsh, associated with Roman imperial history, and it formed the centre of the new royal administration of North Wales. Edward's birth brought predictions of greatness from contemporary prophets, who believed that the Last Days of the world were imminent, declaring him a new King Arthur, who would lead England to glory. David Powel, a 16th-century clergyman, suggested that the baby was offered to the Welsh as a prince "that was borne in Wales and could speake never a word of English", but there is no evidence to support this account.

Edward's name was English in origin, linking him to the Anglo-Saxon saint Edward the Confessor, and was chosen by his father instead of the more traditional Norman and Castilian names selected for Edward's brothers: John and Henry, who had died before Edward was born, and Alphonso, who died in August 1284, leaving Edward as the heir to the throne. Although Edward was a relatively healthy child, there were enduring concerns throughout his early years that he too might die and leave his father without a male heir. After his birth, Edward was looked after by a wet nurse called Mariota or Mary Maunsel for a few months until she fell ill, when Alice de Leygrave became his foster mother. He would have barely known his natural mother, Eleanor, who was in Gascony with his father during his earliest years. An official household, complete with staff, was created for the new baby, under the direction of a clerk, Giles of Oudenarde.