The character 'Dr. Polidori' is not taken from Mary Shelley's novel, but was a real life acquaintance of hers. He started to write "The Vampyre" in the same weekend that she got the idea to write "Frankenstein". The actual Polidori served as Lord Byron's doctor at the time, who mockingly referred to him as 'Pollydori', just like Clerval does in this TV adaptation.