Sigourney Weaver is being sought as a female Doctor Who by British TV producers, who are keen to change the sex of the cult time-traveller. Scriptwriter and executive producer RUSSELL T DAVIES insists the Hollywood superstar would be perfect for the role, but fears he could never afford her. He says, "I would love to get a gripping US star like Sigourney Weaver. "But you often get an actor who says, 'I would love to be in it,' and then you have to speak to the agent." British actor David Tennant currently occupies the lead role in the BBC series.