Lord Ruthven is a fictional character. First appearing in print in 1816, he was one of the first vampires in English literature.
There is a genuine title of Lord Ruthven of Freeland in the Peerage of Scotland which is a subsidiary title of the Earl of Carlisle in the United Kingdom. The fictional characters are not related to the historical title holders.
The first fictional Lord Ruthven appeared in the 1816 Gothic novel Glenarvon by Lady Caroline Lamb. This character was based on the genuine Lord Byron and was not a vampire. Lady Caroline was a former lover of Lord Byron's and the novel did not offer a flattering portrait.
Lord Ruthven appeared as the titular character in the 1819 short story "The Vampyre". This had been written in 1816 by Dr. John William Polidori, the traveling doctor of Lord Byron. It was published in the April 1, 1819 edition of The New Monthly Magazine. The publishers falsely attributed the authorship to Byron. Both Byron and Polidori disputed this attribution. In the following issue, dated May 1, 1819, Polidori wrote a letter to the editor explaining "that though the groundwork is certainly Lord Byron's, its development is mine."
In the story, a young Englishman Aubrey meets Lord Ruthven, a man of mysterious origins who has entered London society. Aubrey accompanies Ruthven to Rome, but leaves him after Ruthven seduces the daughter of a mutual acquaintance. Aubrey travels to Greece where he becomes attracted to Ianthe, an innkeeper's daughter. Ianthe tells Aubrey about the legends of the vampire. Ruthven arrives at the scene and shortly thereafter Ianthe is killed by a vampire. Aubrey does not connect Ruthven with the murder and rejoins him in his travels. The pair are attacked by bandits and Ruthven is mortally wounded. Before he dies, Ruthven makes Aubrey swear an oath that he will not mention his death or anything else he knows about Ruthven for a year and a day. Looking back, Aubrey realizes that everyone who Ruthven met ended up suffering.