British actor Christopher Eccleston kicked off the Doctor Who revival back in 2005 as the first 21st century incarnation of the Doctor. Plenty of modern folks knew nothing of the Doctor Who mythology about Time Lords and the TARDIS and regeneration, so it fell to Eccleston to hook audiences into the series. Without Eccleston's performance as the Ninth Doctor, we might not have gotten a Tenth or Eleventh or Twelfth. Sadly, he only stayed on board as Nine for a single season due to some personal issues with production. Recently, Eccleston had this to say about his biggest Doctor Who regret:
Considering some of Christopher Eccleston's key performances in his first and only season, it's hard to imagine that he could have improved much. He managed to portray a character who was very clearly an alien while also devastatingly human. Despite not being known for playing comedy prior to tackling the role of the Doctor, Eccleston increasingly found ways to infuse lightness into some very dark subject matter. He's certainly not the only person who thinks it was a tragedy that he left Doctor Who after just the one season. His reveal on Drive with Raf Epstein is definitely bittersweet.
Of course, Christopher Eccleston has not been shy about explaining why he left Doctor Who after one season. He shared in the past that he and the producers had very different ideas about where the series should go, and time has clearly not lessened his displeasure with how production was handled during his time on the show. Add on the fact that he didn't want to get stuck into a single role for years and years, and he decided that one season was enough for him. He even chose not to reprise the role of Nine for the 50th anniversary special that brought David Tennant back as Ten for an adventure with Eleven. We can now only wonder what might have been if Christopher Eccleston hadn't moved on from Doctor Who after Season 1.
On the whole, however, Doctor Who may have benefited from Christopher Eccleston's early departure. I'll admit that I shed more than a few tears when Nine dropped his final "fantastic!" and turned into David Tennant, but the regeneration of Nine to Ten was a perfect way to introduce new Who viewers to one of the most unique aspects of the Doctor.
We needed to understand that the Doctor wouldn't die in the traditional sense as much as Rose did, and learning about it wouldn't have been nearly as unforgettable as witnessing it. It was heartbreaking to see the end of Nine when he had so many more adventures through time and space ahead of him, but it worked to see him go and regenerate into Ten.
Christopher Eccleston is the only revival Doctor to date who only stayed on for one season. Ten and Eleven lasted years before regenerating, and Twelve doesn't seem to be going anywhere any time soon. Still, Nine won't be forgotten for as look as people continue to watch the revival that Eccleston launched back in 2005.