Torchwood creator Russell T. Davies has suggested that he may leave the show.
The writer told BBC News that he will likely move on to other projects once new ten-part series Miracle Day is complete.
"It's interesting as to how long I can stay in the science fiction world," he said. "Personally I think I'm coming to the end of it now and I've saved the world and blown up the world too many times."
Davies added that he hopes to leave the series in "rude health" for other writers to take over.
"It's time to write something just where people talk in kitchens, at least for me," he insisted. "But I hope we literally leave the franchise in a very strong position [so] that other writers come in and take it over."
However, he admitted that it had been "brilliant" to return to the show for potentially the final time.
"In a way for me, Torchwood never went away because it always lives in my head," he explained. "Eve Myles's character Gwen Cooper and obviously Captain Jack, played by John Barrowman, it's their fourth year of stories now. It's kind of like they have become modern legends. I love that."
Torchwood: Miracle Day will air on BBC One in the UK and Starz in the US.