Dracula is a work of fiction, but it does contain some historical references; although it is a matter of conjecture and debate as to how much historical connection was deliberate on Stoker's part.
Attention was drawn to the supposed connections between the historical Transylvanian-born Vlad III Dracula (also known as Vlad Tepes) of Wallachia and Bram Stoker's fictional Dracula, following the publication of In Search of Dracula by Radu Florescu and Raymond McNally in 1972.
During his main reign (1456–1462), "Vlad the Impaler" is said to have killed from 40,000 to 100,000 European civilians (political rivals, criminals, and anyone that he considered "useless to humanity"), mainly by impaling. The sources depicting these events are records by Saxon settlers in neighbouring Transylvania who had frequent clashes with Vlad III. Vlad III is revered as a folk hero by Romanians for driving off the invading Ottoman Turks, of whom his impaled victims are said to have included as many as 100,000. There is no solid evidence that the Count in the novel was modelled on Vlad the Impaler of Wallachia. At most, Stoker borrowed only the name Dracula and "scraps of miscellaneous information" about Romanian history, according to one expert, Elizabeth Miller; as well, and there are no comments about him in the author's working notes. 
Historically, the name "Dracula" is derived from a Chivalric order called the Order of the Dragon, founded by Sigismund of Luxembourg (then king of Hungary) to uphold Christianity and defend the Empire against the Ottoman Turks. Vlad II Dracul, father of Vlad III, was admitted to the order around 1431, after which Vlad II wore the emblem of the order and later, as ruler of Wallachia, his coinage bore the dragon symbol, from which the name "Dracula" is derived since "dracul" in Romanian means "the dragon". People of Wallachia only knew voievod (king) Vlad III as Vlad Țepeș (the Impaler). The name "Dracula" became popular in Romania after publication of Stoker's book. Contrary to popular belief, the name Dracula does not translate to "son of the devil" in Romanian, which would be "fiul diavolului".
Stoker came across the name Dracula in his reading on Romanian history, and chose this to replace the name (Count Wampyr) originally intended for his villain. Some Dracula scholars led by Elizabeth Miller argue that Stoker knew little of the historic Vlad III except for the name "Dracula" in addition to a few bits of Romanian history. Stoker mentions that his Dracula fought against the Turks and was later betrayed by his brother, historical facts in the novel which point to Vlad III:
Who was it but one of my own race who as Voivode crossed the Danube and beat the Turk on his own ground? This was a Dracula indeed! Woe was it that his own unworthy brother, when he had fallen, sold his people to the Turk and brought the shame of slavery on them! Was it not this Dracula, indeed, who inspired that other of his race who in a later age again and again brought his forces over the great river into Turkey-land; who, when he was beaten back, came again, and again, though he had to come alone from the bloody field where his troops were being slaughtered, since he knew that he alone could ultimately triumph! (Chapter 3, pp. 19)
The Count's identity is later speculated on by Professor Van Helsing:
He must, indeed, have been that Voivode Dracula who won his name against the Turk, over the great river on the very frontier of Turkey-land. (Chapter 18, p. 145)
Many of Stoker's biographers and literary critics have found strong similarities to the earlier Irish writer Sheridan Le Fanu's classic of the vampire genre Carmilla. In writing Dracula, Stoker may also have drawn on stories about the sídhe, some of which feature blood-drinking women. The Irish legend of Abhartach has also been suggested as a source.It is also thought probable that his mothers stories of events during the severe cholera outbreak in Sligo in 1832 were influential. Particularly themes of being buried while alive.
In 1983, McNally additionally suggested that Stoker was influenced by the history of Hungarian Countess Elizabeth Bathory, who allegedly tortured and killed between 36 and 700 young women. It was later a commonly believed rumor that she committed these crimes to bathe in their blood, believing that this preserved her youth.
In her book The Essential Dracula, Clare Haword-Maden suggested that the castle of Count Dracula was inspired by Slains Castle, at which Bram Stoker was a guest of the 19th Earl of Erroll. According to Miller, he first visited Cruden Bay in 1893, three years after work had begun on Dracula. Haining and Tremaine maintain that, during this visit, Stoker was especially impressed by Slains Castle's interior and the surrounding landscape. Miller and Leatherdale question the stringency of this connection.
Possibly, Stoker was not inspired by a real edifice at all, but by Jules Verne's novel The Carpathian Castle (1892) or Anne Radcliffe's The Mysteries of Udolpho (1794). A third possibility is that he copied information about a castle at Vécs from one of his sources on Transylvania, the book by Major E.C. Johnson. A further option is that Stoker saw an illustration of Castle Bran (Törzburg) in the book on Transylvania by Charles Boner, or read about it in the books by Mazuchelli or Crosse.
Many of the scenes in Whitby and London are based on real places that Stoker frequently visited, although he distorts the geography for the sake of the story in some cases. One scholar has suggested that Stoker chose Whitby as the site of Dracula's first appearance in England because of the Synod of Whitby, given the novel's preoccupation with timekeeping and calendar disputes.
Daniel Farson, Leonard Wolf, and Peter Haining have suggested that Stoker received much historical information from Ármin Vámbéry, a Hungarian professor whom he met at least twice. Miller argues, "there is nothing to indicate that the conversation included Vlad, vampires, or even Transylvania", and "furthermore, there is no record of any other correspondence between Stoker and Vámbéry, nor is Vámbéry mentioned in Stoker's notes for Dracula."