2022–present: The Gilded Age
In April 2015, The Hollywood Reporter reported that Fellowes was at work on a new period drama series for NBC television, to be set in late 19th-century New York City, entitled The Gilded Age. Fellowes suggested that a younger version of Maggie Smith's Dowager Countess character from his Downton Abbey drama might appear in the new series, saying: "Robert Crawley would be in his early teens, Cora would be a child. A young Violet [the Dowager Countess] could make an appearance." As the title suggests, the series would be set during the time of America's so-called Gilded Age – the industrial boom era in the United States in the late 19th and early 20th centuries – and portray the upper echelons of New York's high society during that period.
Production and writing for The Gilded Age was updated in January 2016 indicating that filming would start at the end of 2016. As reported in RadioTimes: "NBC's The Gilded Age is set to start shooting later this year, Fellowes tells RadioTimes.com. Asked whether he'd written the script yet, Fellowes replied, 'No I haven't, no. I'm doing that this year', before adding: 'And then hopefully shooting at the end of the year.'" In April 2016, it was announced that Fellowes would be the producer of The Gilded Age when it was reported that Fellowes is "about to begin writing The Gilded Age for NBC, a sort of American Downton about fortunes made and lost in late 19th century New York, which he will also produce."
On 4 June 2016, Fellowes was asked by The Los Angeles Times, "Where does The Gilded Age stand?" Fellowes replied,
It stands really with me up to my neck in research, and I'm clearing the decks, so that when I start Gilded Age, I'm only doing Gilded Age. These people were extraordinary. You can see why they frightened the old guard, because they saw no boundaries. They wanted to build a palace, they built a palace. They wanted to buy a yacht, they bought a yacht. The old guard in New York weren't like that at all, and suddenly this whirlwind of couture descended on their heads. The newcomers redesigned being rich. They created a rich culture that we still have – people who are rich today are generally rich in a way that was established in America in the 1880s, '90s, 1900s. It was different from Europe. Something like Newport would never have happened in any other country, where you have huge palaces, and then about 20 yards away, another huge palace, and 20 yards beyond that another huge palace. In England right up to the 1930s, when people made money, they would buy an estate of 5,000 acres and they'd have to look after Nanny. The Americans of the 1880s and '90s didn't want too much of that.
In August 2016, Fellowes indicated that his plans for The Gilded Age would not overlap substantially with the characters in Downton Abbey since most of them would have been children in those earlier "prequel" decades. Writing for Creative Screenwriting, Sam Roads asked Fellowes, "Will there be any connection between The Gilded Age and Downton Abbey?" to which Fellowes stated:
I can't see it really. Someone asked if you would you see any of the Downton characters, but most of them would be children. They said that Violet wouldn't be a child, and I replied that "Yes, I suppose you could see a younger Violet", and this became a newspaper story. "Violet comes from Downton to appear in The Gilded Age!" It might be fun, but I doubt at the beginning, because I want it to be a new show with new people.
Fellowes wrote an adaptation of the novel Doctor Thorne by one of his favorite writers, Anthony Trollope. The ITV adaptation aired on 6 March 2016. A report in early September 2018 stated that Fellowes had two projects underway, both in development: the Netflix series The English Game and The Gilded Age for NBC. In May 2019, The Gilded Age moved to HBO, and it premiered in January 2022.