Doctor Who star David Tennant has signed a $1.8 million (GBP1 million) contract to shoot a third series of the sci-fi show - but he will quit for Hollywood after it has finished. Tennant took on the role after Christopher Eccleston left after just one series - and the Harry Potter AND THE GOBLET OF FIRE star helped make the TV show a ratings winner. Tennant has committed to another season, but is not expected to stay with the show after a flood of movie offers from Hollywood. A insider says, "David absolutely loves the programme but if it comes back for a fifth season bosses will have to find a new Doctor Who."