Bob
"Bob" is the Secretary of the Ankh-Morpork League of Temperance and a Black Ribboner. He has unhealthily long fingernails and a bald head. In fact, in the drawings by Paul Kidby he looks just like Nosferatu. Inference from another line drawing is that he is seeking to blend into human society by keeping pets. However, what spoils the illusion is that these are two huge attack dogs with ferociously spiked collars who look, to the semi-trained eye, like Rhodesian Ridgebacks, with all this implies re. training and attitudes. Whereas most vampires have inordinately long names and cannot help but continue this tradition even when incognito (such as Ms Jane Mary Betty Ann Pamela von Jones), Bob seems to have really cracked the art of unobtrusive alibis.
However, there is evidence of some correspondance between John "Not-A-Vampire-At-All" Smith the League President and Ms von Jones as to the validity of Bob's claims to vampirism: he sunbathes, buys garlic sausage and you can see his reflection...
Annotation
Possibly conflated into the person of John "Not-A-Vampire-At-All" Smith, we have the Roundworld parody religion of the Church Of the SubGenius, which celebrates a Prophet called J.R. "Bob" Dobbs, who is presented as an ordinary All-American Joe with neatly cropped hair and suburban demeanour, who smokes a pipe. But something about Bob's presentation, which might be the slightly manic staring eyes, suggests he's trying just that little bit too hard to blend into humanity...