Downton Abbey is bowing out at the end of the next series although show bosses have admitted they are "contemplating" a film version of ITV's hit period drama.
The show , which attracts an audience of millions of viewers in hundreds of countries, has also been a critical hit winning Golden Globes, Emmys and Bafta awards since its debut in 2010.
Its 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."
The show, filmed at Highclere Castle, features a mixture of established stars including Dame Maggie Smith and helped launch the careers of actors including Michelle Dockery, Lily James and Dan Stevens.
Around 11 million viewers in the UK have regularly 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 also featured guest appearances by names including Kiri Te Kanawa, Shirley MacLaine and - in a sketch for an ITV charity show - George Clooney.
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."
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".
Mr Neame said the final series would have nine episodes, with the last one shown on Christmas Day.
Asked about a possible Downton film, he said: "We would be very interested in that. It's definitely something we're contemplating."
Mr Neame said: "T he cast are excited to move on and see what's next, we all are, but it's tinged with sadness".
He said Lord and Lady Carnarvon, who own Highclere Castle, had been " incredibly patient" while the show was being made.
He said: "I think in one sense they'll be relieved to see all the cameras and trucks pull out of their drive and I think like the rest of us they'll miss a lot of the experience."