A festive tradition of Doctor Who, both Davies and Moffat have mixed reviews from their Christmas episodes. Both however do have a hugely acclaimed one in 'The Christmas Invasion' and 'A Christmas Carol' respectively. 'The Christmas Invasion' not only featured killer santas - that would appear again the following year - but it was overtly Christmassy. Davies seemed to take this approach of centring his stories specifically at Christmas, whereas Moffat's just happen to be set at Christmas; even 'A Christmas Carol' borrows elements from a Seventh Doctor novel that Moffat wrote. Both Davies and Moffat bring out a guest star in their Christmas specials; the former having written a part specifically for Kylie Minogue, and the latter casting Michael Gambon as Kazran Sardick. Again though, Davies uses his stars more to play off David Tennant, and Moffat focusses more on a plot; Christmas episodes are usually good ones to spot tropes from writers, as they're standalone and used to introduce new viewers as well as cater for fans.
