John William Polidori, a friend of Mary Shelley.

"Dr. John Polidori's short story "The Vampyre," first published in New Monthly Magazine in 1819, was the first vampire story in English prose. It inspired a surge of popular interest in vampires, essentially creating the now-familiar image of the vampire as a seducer, an irresistible synthesis of sex and death. Although Polidori is the author of "The Vampyre," the original story idea is not his own. It came about during a gathering of writers, including Lord Byron and Mary Shelley, while Dr. Polidori was serving as Byron's traveling physician. In June of 1816, the authors, trapped inside due to bad weather, challenged each other to write ghost stories. Mary Shelley's story developed into the novel Frankenstein, while Polidori's own fragment became his novel Ernestus Berchtold; or, The Modern Oedipus, published in 1819."

-Sherene Boodram

Source-http://victorian-fiction.suite101.com/article.cfm/the_vampyre_by_john_william_polidori