Steven Moffat is planning a shake up in the Doctor Who world for season 8, and the showrunner recently gave a few hints as to why.

Now that Matt Smith's Eleventh Doctor has regenerated, the series is heading in a new direction with a fierce, older Doctor in the form of Peter Capaldi. Introduced at the end of "The Time of the Doctor" Christmas special, Capaldi's Twelfth iteration of the Time Lord will kickoff the season 8 by giving fans a glimpse of a man they haven't seen since the Ninth Doctor.

'Doctor Who' Season 8 Spoilers: First Clip From Premiere, Peter Capaldi Dons A Nightgown In Behind-The-Scenes VIDEO

"There would be little point in making as radical a change as we've made unless you're going to go quite different with the Doctor," Moffat told Doctor Who Magazine (via CultBox) "Our vague idea is... the last two Doctors have been brilliant, and have been your 'good boyfriend' Doctors. But the Doctor isn't always like that. There is the sort of Tom Baker, Christopher Eccelston end of the spectrum, where he is mad and dangerous and difficult."

'Doctor Who' Season 8 Spoilers: PHOTO From First Day Of Filming, Peter Capaldi 'Slightly Nervous' As He Becomes Twelve [VIDEO]

Moffat, who has headed the series since 2010 after Russell T. Davis left the post, is entering his fourth season and is looking to keep the series fresh, according to Cult Box. Meanwhile, io9 is already compiling a list of possible replacements for the Sherlock creator. Amongst the sites' predictions are Being Human creator Toby Whithouse, Sherlock co-creator Mark Gatiss, and Misfits creator Howard Overman.

Doctor Who is expected to return in the early fall. Click the video below to see Eleven regenerate into Twelve.