The second season of "Doctor Who" has just finished its run on the SciFi Channel and the third season is expected to make its debut in the UK in early 2007, but it looks like once that season is done, it could be the end of the line for series star David Tennant.

Just a couple of weeks after Tennant took the title of the best Doctor Who ever in the official Who magazine, various sources have said that the Scottish actor will end his run with the series in the middle of the fourth season. A spokeswoman for the BBC, however, denied the reports, stating that a fourth season of the series has not yet been considered.

"David is absolutely committed to the show and is currently filming the third [season]," she said. There is no fourth [season] currently commissioned yet so we could not confirm his involvement in that yet.

Season 3 of the long-running sci-fi series is expected to return to BBC1 in March, and will not only see the introduction of new companion Martha Jones (played by Freema Agyeman), but also will feature a range of special guest appearances.

Miranda Raison, known to UK audiences as sleuth Jo Portman from Spooks, is set to appear in the series, alongside Holby City's Hugh Quarshie and Ryan Carnes of Desperate Housewives fame.

The third season of the show will also feature a two-part episode set in 1930s New York City where the lone survivor from the Dalek Cult of Skaro will attempt to return his race to its former glory.

"This time, their plan is the most audacious Dalek scheme yet! said Executive Producer Russell T. Davies. Even the Doctor finds himself out of his depth."