Pointless co-host Richard Osman's debut novel The Thursday Murder Club was the UK's best-selling book in the last full week before Christmas.
The murder mystery sold 134,500 copies in the week up to Saturday.
That's more than double the next biggest seller - Barack Obama's memoir A Promised Land, which sold 66,500.
David Walliams, who has been at number one for three of the past four Christmases, is at number three with Code Name Bananas, on 55,000 sales.
Osman's book had the highest sales for a Christmas number one since Jamie Oliver a decade ago, according to The Bookseller, and is the first debut novel to be Christmas number one since current records began in the late 1990s.
The Thursday Murder Club has sold almost 700,000 copies in less than four months, according to publishers Penguin, making it the third best-selling hardback novel after Dan Brown's The Lost Symbol and JK Rowling's Harry Potter and the Deathly Hallows.
"Lots of celebrities have written novels in the past, but his book has been cheered by literary critics and the public alike," The Bookseller's managing editor Tom Tivnan said.
"It crosses all parts of the industry. Celebrity novels generally do well in supermarkets and on Amazon, but it's been the best-selling book in independent book shops since it's been on sale. It's been selling massively since day one, for four months straight, which is really rare."
Osman has a combination of celebrity name recognition and word-of-mouth success, Mr Tivnan said.
"He has a wide appeal - from university kids who watch him during the afternoon to pensioners. The main thing, though, is the book is good. It's a cracking read. It would have sold well if the book was just a passable thriller. But everyone who reads it presses it on to other people."
UK top 10 books
- Richard Osman - The Thursday Murder Club, 134,514 copies sold
- Barack Obama - A Promised Land, 66,531
- David Walliams - Code Name Bananas, 55,129
- Kay Featherstone & Kate Allinson - Pinch of Nom: Quick & Easy, 52,955
- Charlie Mackesy - The Boy, The Mole, The Fox and The Horse, 52,099
- Guinness World Records 2021, 35,229
- Douglas Stuart - Shuggie Bain, 31,218
- JK Rowling - The Ickabog, 31,159
- David Jason - A Del of a Life, 23,973
- David Attenborough - A Life on Our Planet, 23,686
Source: Nielsen Book Research. Week ending 19 December.
The Thursday Murder Club tells the story of four elderly friends in a retirement village who investigate unsolved murders. Osman has signed a deal to write two follow-ups, and Steven Spielberg has bought the film rights.
Osman is also known as the question-master on TV quiz show Pointless and the host of House of Games.
On Monday, he announced that he is leaving his day job as creative director of TV production company Endemol UK.
I'm aware that people who think I'm a TV presenter didn't even know I had an actual, real job, but there we are.— Richard Osman (@richardosman) December 21, 2020
UK shoppers spent £90m on 9.6 million books last week, according to Nielsen Book Research.
Total book sales this year are likely to be down by around 6%, according to Mr Tivnan, which he said was "a decent result" given how long book shops have been closed because of lockdowns.