Tina
Yes, Edgar Allan Poe is well known in the UK - in fact he lived in England and Scotland for a while when he was young and went to school in Stoke Newington.
Did you mention Mary Shelley and Bram Stoker because you think of them as writers of horror? Shelley's 'Frankenstein' is much more of a philosophical work, and Stoker's 'Dracula' something of a ripping yarn. Also they are both novels, while Poe is much better known for poetry and short stories. There are numerous other writers of horror in the UK and Ireland including Sheridan le Fanu, the Benson brothers, M R James, the master of the ghost story, Polidori who wrote the first romantic vampire story in English - and, for macabre poetry there is Thomas Lovell Beddoes.
Ray
It really depends what you mean by "famous".
None of them are wildly "famous". Most people know Frankenstein's monster (who they often think is *called* Frankenstein) and Dracula as fictional monsters, but quite a few don't know the authors. Poe is kind of well-known, but again he's most known vaguely as the author of The Raven and, if you're a horror fan, for being the original author behind the series of overblown Roger Corman films. *If* people know of him, his UK reputation is as a sad geek obsessed with underage dying women - and not as a highly intelligent writer who was one of the originators of the detective story genre.