Sir Harry Paget Flashman VC, KCB, KCIE is a fictional character created by Thomas Hughes (1822–1896) in the semi-autobiographical Tom Brown's School Days (1857) and later developed by George MacDonald Fraser (1925–2008). Harry Flashman appears in a series of 12 of Fraser's books, collectively known as The Flashman Papers, with covers illustrated by Arthur Barbosa and Gino D'Achille. Flashman was played by Malcolm McDowell in the Richard Lester 1975 film Royal Flash.

In Tom Brown's School Days (1857), Flashman is portrayed as a notorious Rugby School bully who persecutes Tom Brown and is finally expelled for drunkenness, at which point he simply disappears. Fraser decided to write the story of Flashman's later life, in which the school bully would be identified as an "illustrious Victorian soldier", experiencing many of the 19th-century wars and adventures of the British Empire and rising to high rank in the British Army, to be acclaimed as a great warrior, while still remaining "a scoundrel, a liar, a cheat, a thief, a coward—and, oh yes, a toady." In the papers—which are purported to have been written by Flashman and discovered only after his death—he describes his own dishonourable conduct with complete candour. Fraser's Flashman is an antihero who often runs away from danger. Nevertheless, through a combination of luck and cunning, he usually ends each volume acclaimed as a hero.

Fraser gave Flashman a lifespan from 1822 to 1915 and a birth-date of 5 May. He also provided Flashman's first and middle names, as Hughes's novel had given Flashman only one, using the names to make an ironic allusion to Henry Paget, 1st Marquess of Anglesey. Paget was one of the heroes of Waterloo, who cuckolded the Duke of Wellington's brother Henry Wellesley and later—in one of the period's more celebrated scandals—married Lady Anglesey, after Wellesley had divorced her for adultery.

In Flashman, Flashman says that his great-grandfather, Jack Flashman, made the family fortune in America, trading in rum, slaves and "piracy too, I shouldn't wonder". Despite their wealth, the Flashmans "were never the thing"; Flashman quotes the diarist Henry Greville's comment that "the coarse streak showed through, generation after generation, like dung beneath a rosebush". Harry Flashman's equally fictional father, Henry Buckley Flashman, appears in Black Ajax (1997). Buckley, a bold young officer in the British cavalry, is said to have been wounded in action at Talavera in 1809, and then to have gained access to "society" by sponsoring bare-knuckle boxer Tom Molineaux (the first black man to contend for a championship). The character subsequently marries Flashman's mother Lady Alicia Paget, a fictional relation of the real Marquess of Anglesey. Buckley, it is related, also served as a Member of Parliament (MP) but was "sent to the knacker's yard at Reform". Beside politics, the older Flashman character has interests including drinking, fox hunting (riding to hounds), and women.

Flashman is a large man, six feet two inches (1.88 m) tall and close to 13 stone (about 180 pounds or 82 kg). In Flashman and the Tiger, he mentions that one of his grandchildren has black hair and eyes, resembling him in his younger years. His dark colouring frequently enabled him to pass (in disguise) for a Pashtun. He claims only three natural talents: horsemanship, facility with foreign languages, and fornication. He becomes an expert cricket-bowler, but only through hard effort (he needed sporting credit at Rugby School, and feared to play rugby football). He can also display a winning personality when he wants to, and is very skilled at flattering those more important than himself without appearing servile.

As he admits in the Papers, Flashman is a coward, who will flee from danger if there is any way to do so, and has on some occasions collapsed in funk. He has one great advantage in concealing this weakness: when he is frightened, his face turns red, rather than white, so that observers think he is excited, enraged, or exuberant—as a hero ought to be.

After his expulsion from Rugby School for drunkenness, the young Flashman looks for an easy life. He has his wealthy father buy him an officer's commission in the fashionable 11th Regiment of Light Dragoons. The 11th, commanded by Lord Cardigan, later involved in the Charge of the Light Brigade, has just returned from India and are not likely to be posted abroad soon. Flashman throws himself into the social life that the 11th offered and becomes a leading light of Canterbury society. In 1840 the regiment is converted to Hussars with an elegant blue and crimson uniform, which assists Flashman in attracting female attention for the remainder of his military career.

A duel with another officer over a French courtesan leads to his being temporarily stationed in Paisley, Scotland. There he meets and deflowers Elspeth Morrison, daughter of a wealthy textile manufacturer, whom he has to marry in a "shotgun wedding" under threat of a horsewhipping by her uncle. But marriage to the daughter of a mere businessman forces his transferral from the snobbish 11th Hussars. He is sent to India to make a career in the army of the East India Company. Unfortunately, his language talent and his habit of flattery bring him to the attention of the Governor-General. The Governor does him the (very much unwanted) favour of assigning him as aide to General Elphinstone in Afghanistan.