Christopher Eccleston quits his role as Dr Who just one day after the BBC ordered a second season of the cult classic.
Eccleston, whose first appearance as the ninth Doctor attracted 10 million viewers, said he feared being typecast.
Bookies have tipped Casanova actor David Tennant as the hot favourite to replace Eccleston as the Time Lord, with odds of 1/10.
Other contenders for the role include Bill Nighy and comedian Eddie Izzard.
Boo Who!