It's a reunion that Terry Nation would be proud of ... probably as long as the colorful iDaleks stay home.

Steven Moffat is bringing every Dalek ever shown in "Doctor Who" to a single episode, the season premiere that kicks off this fall. And Moffat had to turn back to his old boss, former showrunner Russell T. Davies, for help.

Instead of building all the Daleks from over the years from scratch, producers risked the spoiler getting out by doing a casting call for about 20 to 30 prop Daleks, especially those that were used in the television show over the last 49 years. Davies provided a grey and black Dalek that he has kept in his Manchester home since leaving the series in 2009.

That joined a bunch of other Daleks, primarily coming from the Doctor Who Experience. That attraction, which features sets and props from the iconic series, closed its doors in London in February, and is expected to re-open in Cardiff (where the series is currently filmed) this summer.

British tabloid The Sun boasts of its own Dalek prop that was used in a 1972 Jon Pertwee-era episode. However, by the time the newspaper found out about the casting call, the episode had been filmed and it was too late to use it.

"Doctor Who" currently is filming in New York, and is working on its final episodes before work starts on the Christmas special. It's that special where Jenna-Louise Coleman is expected to make her debut as the new companion to Matt Smith.

The Daleks have remained virtually unchanged as characters since their introduction in 1963 in an episode called "The Daleks" written by Nation. The creatures themselves are actually small mutated beings that control an military suit that would be equivalent to a tank.

Daleks are known for their desire to "exterminate," and to ensure that they are by far the dominant sentient species in the universe.

The Daleks had been a part of every season of "Doctor Who" since it returned in 2005 except for last season. In fact, the last appearance of the Daleks was in "The Big Bang," the Season 5 finale that aired in June 2010.

The seventh season of "Doctor Who" -- and the third to feature Smith -- will premiere this fall. It will feature, among other things, a split season over Christmas, as well as the departure of actors Karen Gillan and Arthur Darvill, who play married companions Amy Pond and Rory Williams. They are expected to leave the show ahead of the Christmas break.