Ever heard of the best-selling writers Mark McCrum, Rebecca Farnworth or Pepsy Dening? Their words are seen by millions, but even the most voracious reader is unlikely to know them.
That's because they are ghosts -- writers hired by publishers to pen the autobiographies of celebrities -- and their names are almost always left off the books they have written.
But if you have read Robbie Williams' Somebody Someday, one of Katie "Jordan" Price's three autobiographies or Victoria Beckham's Learning to Fly, you will have consumed the writing skills of, respectively, McCrum, Farnworth and Dening.
Welcome to the world of the ghost writer, an art that has come into the public eye thanks to the Roman Polanski film, The Ghost, a thriller based on the Robert Harris novel of the same name which concerns a journalist (Ewan McGregor) writing up the life story of a former Blair-like prime minister (Pierce Brosnan).
The film lifts the lid on a publishing phenomenon. Tellingly, we never learn the name of McGregor's character -- many ghosts are faceless hacks who only see a small portion of the hefty advance and several sign confidentiality documents with the publisher not to talk about their work.
Penguin Ireland's managing director Michael McLaughlin says there are few celebrities from the worlds of business, sport and entertainment who literally write their own books.
"The fact of the matter is that most celebrities don't have the ability to write about themselves in any way that would interest the reader," he says.
"Their talents are in other areas and that's why we need writers who are able to write with flair and somehow get inside the head of that person. Good ghost writers are like gold dust."
An insider in Dublin publishing says ghosts themselves are often just as keen as their subject is not to be named.
"Maybe, they're embarrassed to have written certain books or they feel that they are selling out in some way. There are several well known journalists in Dublin who wouldn't want it to be known that they supplement their incomes with ghost writing."
Journalist Eddie Rowley has no problem with anyone knowing that he is a ghost writer. "It's something I enjoy doing," he says. "I have ghost-written the biographies of Daniel O'Donnell and Ronan Keating and I've been credited as the writer. I prefer it that way."
Rowley had written about the pair since the start of their careers and was an automatic choice to be their ghost.
"The subject of the biographer has to trust the ghost writer and feel comfortable with them. I've known both Daniel and Ronan for years, so it made it much easier for all of us."
He says it is harder than it appears to write an interesting biography. "Both of them were generous with their time and were interested in making the biographies as intriguing as possible. The job would be much harder if the subject isn't very talkative or if they are very sketchy with the facts. Those books are difficult for the publisher to promote because they can end up being very anodyne."
A case in point is Wayne Rooney's 2006 autobiography, the first of five books due to be published in his lifetime according to the terms of a stg£5m advance. Despite the enormous wage, the footballer only met his ghost, Hunter Davies, six times.
Davies, who is renowned as a writer in his own right, as well as the man who penned the Paul Gascoigne autobiography, believes even the most talented writer will be unable to fashion anything interesting from mundane celebrities.
"The vital thing a ghost writer needs," according to Davies, "more than their pots and medals, more even than their so-called celebrity, is a good talker who enjoys telling stories and is not ashamed or scared to reveal himself. And you need a rich life, with a variety of experiences -- ups and downs."
Ghost writing first came to prominence in the 1920s around the time that "celebrity" was born. Baseball legend Babe Ruth had syndicated ghost-written columns published across the US. Such columns appear in the sports columns of newspapers the world over today.
And publishers soon cottoned on to the fact that celebrity autobiographies would sell even if the celebrity was still in their infancy -- think Kerry Katona and Shayne Ward. The former published a ghosted novel in 2008.
"Ronan's biography sold 300,000 in the UK alone," Rowley says, and those are the figures that really excite publishers. "Very often, it's ghost written autobiographies that top the charts on both sides of the Atlantic. There is huge appetite for those sort of books."
For top international ghosts, six-figure fees can be paid, but Michael McLaughlin says Irish ghost-writers tend to be paid in "the thousands, rather than the tens of thousands. Often it's a labour of love for them, but in these difficult times that sort of money is not to be sniffed at."
Much like McGregor's character in the film, not all ghosts enjoy the experience. Robin Eggar, who penned Midge Ure's celebrated autobiography If I Was is succinct in his appraisal: "The problem is you are not in control. It is someone else's story and your job is to make him sound much more articulate than he really is. Midge Ure had been struggling with alcoholism for a while and the experience of exposing his thoughts brought the demons home. It was quite traumatic, but his wife liked the book."
Journalist Bruce Dessau who wrote Blitzed!, the autobiography of Steve Strange, the New Romantic star, is just as blunt: "You really have to check your ego at the door, and my self-obsession was far too big to spend that long listening to someone talk about himself."