Downton Abbey will bow out at the end of the next series, ITV has said.
The hit period drama, which has attracted millions of viewers around the world, is set in an English country house and has made stars of many of its cast.
Creator Julian Fellowes said: "The Downton journey has been amazing for everyone aboard. People ask if we knew what was going to happen when we started to make the first series and the answer is that, of course, we had no idea.
"Exactly why the series had such an impact and reached so many people around the world, all nationalities, all ages, all types, I cannot begin to explain. But I do know how grateful we are to have been allowed this unique experience.
"I suspect the show will always be a principal marker in most of our careers as we set out from here and, if so, I consider that a blessing and a compliment."
Executive producer Gareth Neame said: "Millions of people around the world have followed the journey of the Crawley family and those who serve them for the last five years. Inevitably there comes a time when all shows should end and Downton is no exception.
"We wanted to close the doors of Downton Abbey when it felt right and natural for the storylines to come together and when the show was still being enjoyed so much by its fans. We can promise a final season full of all the usual drama and intrigue, but with the added excitement of discovering how and where they all end up."
The show regularly pulls in around 11 million viewers in the UK and is viewed in hundreds of countries around the world.
It has won Golden Globes, Emmys and Bafta awards along the way.
ITV's director of television, Peter Fincham, said: "When Julian Fellowes and Gareth Neame brought us the idea for Downton Abbey six years ago, we thought it would be a great Sunday night series for ITV, but we had no way of knowing that it would become a global phenomenon playing to hundreds of millions of viewers around the world.
"What a ride it's been - for everyone involved in the production, for the cast, and most of the all for the audience.
"We all thought very carefully about the right moment to bring something so special to a close that felt editorially right, and left viewers wanting more.
"Christmas Day on ITV this year will certainly be one to remember, as the concluding special brings a series to an end that started as a leap of faith for all of us, and ended surpassing all expectations."
The show, filmed at Highclere Castle, features a mixture of established stars including Dame Maggie Smith and up-and-coming actors.
It has followed the fortunes of the Crawley family, and the people who work for them, from the sinking of The Titanic through the First World War and beyond.
It has helped launch the careers of actors including Michelle Dockery, Lily James and Dan Stevens, and featured guest appearances by names including Kiri Te Kanawa, Shirley MacLaine and - in a sketch for an ITV charity show - George Clooney.
Mr Neame told reporters the show had "always tried to get its timing right".
He said: "I think our feeling is that it's good to quit while you're ahead", adding that he did not want viewers to think the show had "outstayed its welcome".