[2] In 1816, which became known as the Year Without a Summer, Polidori entered Lord Byron's service as his personal physician and accompanied him on a trip through Europe.

One night in June after the company had read aloud from Fantasmagoriana, a French collection of German horror tales, Byron suggested they each write a ghost story.

[4] Polidori's conversation with Percy Bysshe Shelley on 15 June 1816, as recounted in The Diary, is regarded as the origin or genesis of Frankenstein.

His story, "The Vampyre", which featured the main character Lord Ruthven, was published in the April 1819 issue of New Monthly Magazine without his permission.

Despite conjecture from his family that he died by suicide by means of prussic acid, the coroner gave a verdict of death by natural causes.

Based only on the transcription, The Diary of John Polidori was edited by William Michael Rossetti and first published in 1911 by Elkin Mathews (London).

[11] A memorial plaque on John Polidori's home at 38 Great Pulteney Street was unveiled on 15 July 1998 by the Italian Ambassador, Paolo Galli.