David Tennant and Catherine Tate are to return to Doctor Who, the BBC has confirmed.
The pair are currently filming for the sci-fi show's 60th anniversary, which it will celebrate in 2023.
Tennant played the 10th Doctor on the time travel drama from 2005-2010, while Tate played companion Donna Noble.
The news comes a week after the BBC announced that Sex Education star Ncuti Gatwa will be the next Doctor.
Tennant and Tate's involvement means they will be reunited with returning Doctor Who head writer Russell T Davies.
Davies, who was in charge of Doctor Who when it was successfully revived in 2005, left at the same time as Tennant. Their last episode together was broadcast in 2010.
Tennant has briefly returned before, joining then-Doctor Matt Smith for the programme's 50th anniversary in 2013.
It's not clear at this stage whether this return will be a similar one, with Tennant and Tate appearing alongside Gatwa.
Davies has teased fans, saying: "Maybe this is a missing story. Or a parallel world. Or a dream, or a trick, or a flashback. The only thing I can confirm is that it's going to be spectacular, as two of our greatest stars reunite for the battle of a lifetime."
Tennant and Tate's 2008 series of Doctor Who is the most successful that the show has had since its revival in 2005, with an average audience of more than eight million viewers per episode.
The 13-episode run also enjoyed a high degree of critical acclaim, and was nominated for best drama at that year's Bafta TV Awards.
The pair's popularity may well provide a ratings boost for a show which has seen its audience fall in the last two years, albeit against a background where all linear TV viewing has been dropping significantly.
Announcements such as this are often made ahead of Doctor Who imminently filming in public places. Revealing information ahead of shooting is a strategy that the show has used before.
Jodie Whittaker's current incarnation of the Doctor will appear in one more special episode later this year, as part of a collection of programmes celebrating the BBC's centenary. The show will then return in 2023.
Since leaving Doctor Who, Tennant has appeared in TV series including Good Omens, Around the World in 80 Days and Broadchurch. In 2021, he won a National Television Award for playing serial killer Dennis Nilsen in Des.
Tate has appeared in sitcoms like Big School, and has continued performing her well known Nan character - most recently in The Nan Movie released earlier this year.
The pair have also recorded a number of Doctor Who audio adventures which have been released by audio drama company Big Finish.