The stunning success of Doctor Who means the series has become part of the tourist campaign for Wales.
As well as being one of BBC Wales' biggest success stories and helping rejuvenate Saturday night television, Doctor Who has done far more than introduce a whole new generation of fans to the Time Lord.
With many of the scenes filmed on location in Wales, the programme is giving the country a wealth of positive publicity.
The first series, penned by Welsh writer Russell T Davies, was screened earlier this year. It attracted around 10m viewers an episode, which means a huge audience was introduced to Wales through the show.
Tomorrow's Christmas special, in which David Tennant makes his debut as the new Doctor, is expected to be one of the biggest Christmas Day TV ratings-pullers.
Among several Welsh locations viewers will see is Cardiff city centre. Billie Piper, who plays the Doctor's assistant Rose Tyler, is filmed running through the streets.
And in the new series, to be broadcast next year, among the locations which will be beamed onto TV screens throughout the country are Newport's Tredegar House, Gower, and Wales Millennium Centre in Cardiff Bay.
Bosses at Wales Tourist Board are delighted with the exposure the award-winning programme gives the country.
They believe it can help attract additional visitors to the area as well as give those living in Wales a boost when they see familiar locations beamed onto their TV screens.
And, perhaps even more importantly, filming in Wales gives the economy a boost.
'Having a highly popular TV series like Doctor Who shot on locations in Cardiff and other parts of South Wales helps viewers in Wales feel that they live in a modern and attractive part of the UK,' said a spokesman for the Wales Tourist Board.
'In addition, given that nine out of 10 visitors to Wales come from elsewhere in the UK, scenes of Cardiff and the surrounding area shown on Doctor Who could attract visitors and help Wales maintain its share of the tourism market.
'As far as the economy is concerned, when films and TV programmes are shot on location, the cast and crews spend money on local hotels and restaurants, giving the local economy a boost.'
In the new series, Doctor Who fans may recognise Cardiff Bay's £106m arts venue, Wales Millennium Centre.
Bosses at the centre are delighted the programme's producers decided to film there once again.
'To feature on Doctor Who for the second time in a year is a great profile boost not only for Wales Millennium Centre but for Wales as a nation,' said WMC chief executive Judith Isherwood.
'Such exposure can only increase this world class, iconic performing arts centre's status both nationally and internationally and help make the centre an instantly recognisable symbol for Wales.'
Cardiff Council is also pleased with the benefits the city is reaping from being featured on Doctor Who.
'I think it's raised our profile nationally, internationally and universally as well,' said Nigel Howells, council member for leisure, culture and sport.
'When we first heard Doctor Who was being filmed in Cardiff we were all very excited but I don't think we understood just how great the benefits would be.
'It's really put us on the map. Many people are now coming to Cardiff just to follow in the footsteps of Doctor Who himself.'
During the next two months, Doctor Who fans will have more of an excuse than ever to visit the Welsh capital as a special exhibition - Doctor Who Up Close - has just opened at the Red Dragon Centre in Cardiff Bay.
Featuring monsters, costumes and props form the series, it's something no real fan of the Time Lord can afford to miss.'
The Doctor Who Christmas Special is on BBC1 tomorrow at 7pm.
The Doctor Who exhibition is running until February 26.
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