Field Marshal Julian Hedworth George Byng, 1st Viscount Byng of Vimy (11 September 1862 – 6 June 1935), was a British Army officer who served as Governor General of Canada, the 12th since the Canadian Confederation.

Known to friends as "Bungo", Byng was born to a noble family at Wrotham Park in Hertfordshire, England and educated at Eton College, along with his brothers. Upon graduation, he received a commission as a militia officer and saw service in Egypt and Sudan before enrolling in the Staff College, Camberley. There, he befriended individuals who would be his contemporaries when he attained senior rank in France. Following distinguished service during the First World War—specifically, with the British Expeditionary Force in France, in the Battle of Gallipoli, as commander of the Canadian Corps at Vimy Ridge, and as commander of the British Third Army—Byng was elevated to the peerage in 1919. In 1921, King George V, on the recommendation of Prime Minister David Lloyd George, appointed him to replace Victor Cavendish, 9th Duke of Devonshire as Canada's governor general, a post he occupied until Freeman Freeman-Thomas, 1st Viscount Willingdon succeeded him in 1926. Byng proved to be popular with Canadians due to his war leadership, though his stepping directly into political affairs became the catalyst for widespread changes to the role of the Crown in all of the British Dominions.

After his viceregal tenure, Byng returned to the UK to be appointed Commissioner of Police of the Metropolis and was promoted within the peerage to become Viscount Byng of Vimy. Three years after attaining the rank of field marshal, he died at his home, Thorpe Hall, on 6 June 1935.

Byng was born at the family seat of Wrotham Park, in Hertfordshire, as the seventh son and 13th and youngest child of George Byng, 2nd Earl of Strafford (who, due to the size of his family, ran a relatively frugal household) and Harriet Elizabeth Cavendish, daughter of Charles Cavendish, 1st Baron Chesham. Until the age of 17, Byng was enrolled at Eton College, although he did not enter the sixth form. At Eton Byng first received the nickname "Bungo"—to distinguish him from his elder brothers "Byngo" and "Bango"—but his time at the college was undistinguished, and he received poor reports; indicative of his attitude towards academics, he once traded his Latin grammar book and his brother Lionel's best trousers to a hawker for a pair of ferrets and a pineapple. Byng later claimed that he had been the school's worst "Scug", the colloquial term for an undistinguished boy.

Byng was from a military family, his grandfather having served with Wellington at the Battle of Waterloo. With three brothers already in the army and another already put up for the 7th Queen's Own Hussars, Byng's father did not think he could afford a regular army commission for his youngest son. Thus, at the age of 17, Byng was instead sent into the militia and on 12 December 1879 commissioned as a second lieutenant into the 2nd (Edmonton) Royal Middlesex Rifles (later the 7th Battalion, King's Royal Rifle Corps). He was promoted to lieutenant on 23 April 1881. During this period, Byng also developed a liking for theatre and music halls, and by the age of twenty had taken an interest in the banjo.

At a meeting of the Jockey Club in 1882, Byng's father was asked about his sons by his long-time friend, Albert Edward, Prince of Wales. Upon hearing that Byng had not yet found a permanent career, the Prince offered a place for him in his own regiment, the 10th Royal Hussars. This was the most expensive regiment in the army, and the Earl of Strafford could only afford to give Byng two hundred of the six hundred pounds he would need each year, but the Prince's offer could not be refused. Byng himself was delighted at the opportunity, as both his uncle, William Cavendish, 2nd Baron Chesham, and his cousin, Charles Cavendish, had served in the regiment. By raising money through buying polo ponies cheaply, using his excellent horsemanship to train them, and then selling them on at a profit, Byng was able to transfer to the 10th Royal Hussars on 27 January 1883, and less than three months later he joined the regiment in Lucknow, India.

It was while the regiment was on the way home to Great Britain in 1884 that the Hussars were diverted to the Sudan to join the Suakin Expedition, and on 29 February Byng, along with the rest of his regiment, rode in the first line of the charge at the first Battle of El Teb. The attack, which resulted in the deaths of both of Byng's squadron's other officers, was unsuccessful, and fighting continued, with Byng's horse being killed under him on 13 March at the Battle of Tamai. Most of the rebels were then dispersed shortly after, and on 29 March the regiment re-embarked for Britain, arriving on 22 April, and proceeding to their new base at Shorncliffe Army Camp in Kent. During the summer of 1884, Byng spent much of his time playing polo and training recruits and horses, and in July, for his services in Sudan, he was mentioned in despatches.

In June 1885, the regiment was relocated to the South Cavalry Barracks at Aldershot, where the Prince of Wales' eldest son, Prince Albert Victor, joined the regiment and thereafter the Prince of Wales and his other son, Prince George, became frequent visitors. Byng struck up a friendship with both Albert Victor and George, but did not socialise with them much outside of army circles. Byng was appointed as the regimental adjutant on 20 October 1886, only nine days before the death of his father, who left Byng a watch and £3,500. The regiment then moved again in 1887 to the barracks at Hounslow, where, after suspecting that contractors were selling him inferior meat, Byng spent several early mornings at the Smithfield market to learn the meat trade, eventually proving his case and having the contractors changed. It was also at this time that Byng became acquainted with Montagu Corry, 1st Baron Rowton, who, along with the Guinness Trust, was trying to improve housing for skilled workers in London. Byng accompanied Rowton around the poorest areas of the city and suggested that retired senior soldiers from the rank-and-file be hired to maintain order in the Rowton Houses that Rowton had set up, thus starting a long-lived tradition.