Steven Moffat, head writer and executive producer of "Doctor Who," will leave the series following Season 10, BBC One announced this afternoon. He'll be replaced by "Broadchurch" executive producer Chris Chibnall in 2018.

Why 2018? Because BBC has decided to wait until 2017 to air Moffat's final 12-episode season. Beyond the Christmas special, no new "Doctor Who" episodes are expected to air this year.

“I have decided to schedule Steven’s big finale series in Spring 2017 to bring the nation together for what will be a huge event on the channel," BBC One Controller said in a statement. "2016 is spoilt with national moments including the Euros and Olympics and I want to hold something big back for 2017 -- I promise it will be worth the wait!”

A longtime "Who" fan, Moffat in 2010 followed Russell T Davies as the second showrunner of the revived series, beginning at the same time that Matt Smith assumed the role of the Eleventh Doctor.

“Feels odd to be talking about leaving when I’m just starting work on the scripts for Season 10," Moffat said in a statement, "but the fact is my timey-wimey is running out. While Chris is doing his last run of 'Broadchurch,' I’ll be finishing up on the best job in the universe and keeping the TARDIS warm for him. It took a lot of gin and tonic to talk him into this, but I am beyond delighted that one of the true stars of British television drama will be taking the Time Lord even further into the future.”

No stranger to the TARDIS, Chibnall has written for both "Doctor Who" (notably "42" and "The Hungry Earth"/"Cold Blood") and its spinoff "Torchwood," as well as "Life on Mars" and "Law & Order UK." Before creating "Broadchurch," starring "Who" veteran David Tennant, Chibnall was the showrunner of "Camelot."

"I’ve loved Doctor Who since I was four years old, and I’m relishing the thought of working with the exceptional team at BBC Wales to create new characters, creatures and worlds for the Doctor to explore," Chibnall siad. "Steven’s achieved the impossible by continually expanding 'Doctor Who's' creative ambition, while growing its global popularity. He’s been a dazzling and daring showrunner, and hearing his plans and stories for 2017, it’s clear he’ll be going out with a bang. Just to make my life difficult."