Robert Patrick: Plays a former policeman

The 39-year-old actor's character, FBI agent Fox Mulder, was abucted by aliens at the end of the last series, preparing viewers for his reduced role.

Patrick, best known to Terminator fans as T-1000, will appear alongside regular Gillian Anderson as FBI agent John Doggett, a former policeman who is helping in the search for Mulder.

As well as his role opposite Arnold Schwarzengger in Terminator 2, the 40-year-old's other film credits include The Faculty, Cop Land and forthcoming films Texas Rangers and All The Pretty Horses.

Series creator Chris Carter said: "He's not a replacement for David. He's a new character coming in."

Filming begins next week, with the first episode due to be shown on the US Fox network in November.

The series, about a pair of FBI agents investigating paranormal activities, has been a worldwide hit since it first appeared in 1993. It is shown in the UK on Sky One and BBC One.

Now fans will be looking at the future of the series, as Duchovny and Anderson - who plays Mulder's colleague Dana Scully - are not under contract for a ninth season.

Carter said Patrick's addition would give the producers some options if the show continues beyond next year.