It is generally assumed that stalkers are a product of the modern age, but more than 170 years ago a teenager relentlessly pursued Queen Victoria.
Edward Jones was aged just 14 when he first broke into Buckingham Palace in 1838 and returned twice more to wander around the monarch's private apartment and even steal her personal items.
The teenager gained access to the royal chambers, taking some of the Queen's underwear, and even sat on the throne.
After he had been hauled out from underneath a sofa in her dressing room, the sovereign wrote in her diary: "If he had come into my bedroom, how frightened I would have been".
Jan Bondeson, an expert on London history, has written a book, Queen Victoria's Stalker, which tells the story of the teenager.
The obsessed young man was tried three times and imprisoned twice before the authorities eventually spirited him away to a foreign country to ensure his silence, according to the new book.
Mr Bondeson, a senior lecturer and consultant rheumatologist at Cardiff University, told the Daily Mail: "He sat on the throne, he looked at books in the royal library and he went inside Queen Victoria's private apartments - once he even stole her underwear.
"The amazing thing is really how close he was able to get to the Queen, and the extraordinary lengths the authorities went to to get rid of him.
"They were worried about what the boy Jones might tell people."
The stalker eventually died in 1893 in his seventies after a drunken fall.