Impersonating Salamander, the Doctor infiltrates the research centre, but Benik becomes suspicious. Underground, Salamander's deception is discovered.

Omega intends to escape his antimatter world and needs the Doctors to take his place. But they discover the terrible truth about Omega and realise that he can never escape.

Olivia Hallinan is an English actress best known for her role as Laura Timmins in the BBC TV series Lark Rise to Candleford and also as Kim in the critically acclaimed Sugar Rush. 

She played Emma-Louise Cowell in Torchwood Out of Time

James O'Dee was a stunt performer in Doctor Who.

He is known for his work on Batman Begins (2005), V for Vendetta (2005) and The Hobbit: An Unexpected Journey (2012).

Liza Goddard  is an English television and stage actress

She is best known to Doctor Who fans for her performance as Kari in the 1983 story Terminus and for being the first wife of the Sixth Doctor, Colin Baker.

Goddard is best remembered in Australia for her role as Clarissa "Clancy" Merrick in Skippy the Bush Kangaroo. After returning to the UK in 1969 as an adult, she appeared as Victoria in Take Three Girls (1969), and then its sequel Take Three Women(1982). She also had a supporting role in the 1972 movie Ooh: You Are Awful. Her career breakthrough was as April in The Brothers (1972-76), which also featured her first husband, Colin Baker. 

A comedy role alongside Donal Donnelly in Yes, Honestly (1976-77), by Terence Brady and Charlotte Bingham followed, as did a role, with Christopher Biggins, in an unsuccessful BBC1 sitcom Watch This Space (1980), by Ronald Chesney and Ronald Wolfe. This was followed by Pig in the Middle (1980-83) with Joanna Van Gyseghem. 

After her marriage to Colin Baker, she then married Alvin Stardust and later the producer and director David Cobham (who died in 2018).

Tom Baker was born in Scotland Road, Liverpool. His parents were working class Liverpudlians. Baker left school at 15 to become a Roman Catholic monk and remained in the monastic life for six years, but left after losing his faith, and did his National Service in the Royal Army Medical Corps, serving for two years from 1955 until 1957. 

In the late 1960s and early 1970s Baker was part of Laurence Olivier's National Theatre company, and got his first big film break in 1971 with the role of Rasputin in the film Nicholas and Alexandra. for which he was nominated for two Golden Globe Awards, one for Best Actor in a Supporting Role and another for Best Newcomer. 

In 1974, Baker was cast by Barry Letts to take over the role of the Doctor. Letts was convinced he was right for the part after seeing his performance in The Golden Voyage of Sinbad. He played the Doctor for seven seasons, making him the longest-serving actor in the part so far. T

he manifestation played by Tom Baker (1974-1981) is often regarded as the most popular of the Doctors. In polls conducted by Doctor Who Magazine, Baker has lost the "Best Doctor" category only three times: Once to Sylvester McCoy in 1990, and twice to David Tennant in 2006 and 2009.

Baker returned to the role for a series of five audio dramas for BBC Audio, co-starring Richard Franklin as Captain Mike Yates, which were released in September 1979. He has also played the Fourth Doctor for a series of plays for Big Finish Productions. 

In 2001 Baker was cast as the narrator of Little Britain on BBC Radio 4, and remained in the role when it transferred to television. From 2000 to 2005 Tom voiced the character Max Bear in the Channel 4 (UK) Max Bear Productions animated series. 

More recently, he voiced the role of the villain ZeeBad in the 2005 computer-animated film version of The Magic Roundabout. Baker narrates the children's computer animation series The Beeps which is shown on Five's Milkshake! as well as narrating Tales of Aesop on BBC, a television series based on Aesop's Fables with puppet animation. Baker played Puddleglum, a "marsh-wiggle", in the BBC adaptation of C.S. Lewis' The Silver Chair. 

He also portrayed Sherlock Holmes in a four part BBC miniseries version of The Hound of the Baskervilles in 1982. Baker made a memorable appearance in Blackadder II, as a wild-eyed sea captain who advocated drinking one's own urine as a survival tactic. 

In a 2005 survey of British adults, Baker's voice was found to be the fourth most recognisable after the Queen, Tony Blair and Margaret Thatcher. During the first three months of 2006, his voice was used by BT for spoken delivery of text messages to landline phones. He recorded 11,593 phrases, containing every sound in the English language, for use by the text-to-speech service. His voice may be heard at London's Natural History Museum narrating commentary to some of the exhibits that support Darwin's theory of natural selection.

Baker's autobiography, Who on Earth is Tom Baker? , was published in 1997. He has also written a short fairytale-style novel, The Boy Who Kicked Pigs, which is subtitled "A Grotesque Masterpiece".

Baker's first marriage in 1961 was to Anna Wheatcroft. They had two sons Daniel and Piers, but divorced in 1966 and Baker lost contact with his sons until a chance meeting with Piers in a pub in New Zealand allowing them to renew their relationship. In December 1980 he married Lalla Ward although, the marriage lasted only 16 months. In 1986, Baker married for a third time, this time to Sue Jerrard, who had been an assistant editor on Doctor Who.

Henry Woolf is a British actor, theatre director, and teacher of acting, drama, and theatre

He played  the Collector in the Doctor Who serial The Sun Makers

His film credits include Marat/Sade (1967), The Lion in Winter (1968), Steptoe and Son (1972), Steptoe and Son Ride Again (1973), The Rocky Horror Picture Show (1975), Gorky Park (1983), Superman III (1983). He still makes occasional film appearances, in the 2004 short film, Of Note and in the 2007 short film smallfilm. In All You Need Is Cash, a film by the Rutles (a fictional mock-Beatles band jointly created by Eric Idle and Neil Innes), Woolf played a character named Arthur Sultan, a fictional spoof of Maharishi Mahesh Yogi.

On British television he played the Man in Harold Pinter's one-man play Monologue (1973); parts in Rutland Weekend Television (1975) and The Sweeney (1975); served as the host of the 1970s pre-school British educational series Words and Pictures; and performed the role of Doctor Cornelius in the BBC adaptation of Prince Caspian (1989).

Actor who appeared in the 1971 story Terror of the Autons.

He also had roles in Poldark, The Tomorrow People and Wings of Death.

Ian Scoones was the visual effects designer for several Doctor Who stories in the 1970's

He was assistant to special effects wizard Les Bowie during the 1960's. Worked at Hammer, before joining the BBC in 1970, where he was noted for his work on "Monty Python" and "Doctor Who". In 1980, became special effects supervisor for the "Hammer House of Horror" TV series.

Kevin Stoney was an English actor, best known for his television roles.

He is well remembered by fans of  Doctor Who for his roles in three serials � Mavic Chen in The Daleks' Master Plan (1965), Tobias Vaughnin The Invasion (1968) and Tyrum in Revenge of the Cybermen (1975).  

During World War II, Stoney served with the Royal Air Force.

Stoney also appeared in two episodes of another science fiction series, Blake's 7, playing Councillor Joban in the episode Hostage and Ardus in the episode Animals.

He is also noted for his role as the astrologer Thrasyllus in the 1976 BBC adaptation of I, Claudius, a role he had earlier played in Granada Television's 1969 series The Caesars.

Other credits include: The Adventures of Robin Hood, The Saint, Danger Man, The Avengers, Dr. Finlay's Casebook, The Prisoner, Softly, Softly, Man in a Suitcase, The Troubleshooters, Doomwatch,Freewheelers, Z-Cars, The Tomorrow People, Ace of Wands, Special Branch, The Onedin Line, Fall of Eagles, Space: 1999, The New Avengers, Quatermass, Bergerac, All Creatures Great and Small, The Bill and in the highest rated episode of Inspector Morse.

In 1985, it was reported in the Doctor Who fan magazine, DWB, that Kevin Stoney had died at the age of 64, but in 1987, Stoney made an appearance at a Doctor Who convention to prove he was very much alive, to the shock of the fans.

Kevin Stoney died in Chiswick, after a long battle with skin cancer.

John Maxim appeared in two Doctor Who stories: as Frankenstein's Monster in The Chase and a Cyberman in The Moonbase (under the name John Wills).

Also worked on Il giovane Toscanini, The Prisoner, Frankenstein Created Woman, Dracula: Prince of Darkness, The Big Spender, She, R3, Consider Your Verdict, ITV Television Playhouse, The Frightened City, Mary Had a Little..., William Tell, BBC Sunday-Night Theatre, Ivanhoe