The Third Doctor (1970-1974)
Season Seven 
(1970) Season Seven (1970): Exiled To Earth
First appearances of Liz, the Autons and the Silurians. The Doctor becomes UNIT's scientific adviser. Doctor Who is broadcast in colour for the first time.

Season Ten (1972-73): A Return To Wandering
First multi-Doctor story. The Doctor's exile is lifted.
Season Ten 
(1972-73)
Season Eight 
(1971) Season Eight (1971): Enter -- The Master
First appearances of Jo, Yates and the Master.
Season Eleven (1973-74): Facing Fears
First appearances of Sarah Jane and the Sontarans. The Doctor's home planet is named as Gallifrey for the first time.
Season Eleven 
(1973-74)
Season Nine 
(1972) Season Nine (1972): A Galactic Yo-Yo
First appearance of the Sea Devils.

Season Seven (1970): Exiled To Earth

The Doctor
The Third Doctor

Jon Pertwee portrayed the Doctor from Spearhead From Space in January 1970 to Planet Of The Spiders in June 1974. He returned for The Five Doctors in November 1983 and Dimensions In Time in November 1993. Pertwee passed away in 1996.

Companions and Recurring Characters

Liz Shaw was a brilliant scientist who served as an advisor to UNIT.

Caroline John played Liz from Spearhead From Space in January 1970 to Inferno in June 1970. She returned for The Five Doctors in November 1983 and for Dimensions In Time in November 1993.

Liz Shaw

The Production Team

With Derrick Sherwin eager to rejoin Peter Bryant elsewhere in the BBC ranks, a new producer was appointed early in Season Seven to replace him on Doctor Who. This was Barry Letts, who had previously directed The Enemy Of The World for the series. Together, he and Terrance Dicks became one of the most stable production teams in Doctor Who's history, remaining intact throughout the Pertwee era.

The Stories
Spearhead 
From Space
Spearhead From Space by Robert Holmes, directed by Derek Martinus
The newly-regenerated Doctor is exiled to modern-day Earth by the Time Lords, where he becomes attached to the British branch of UNIT as their scientific adviser, ostensibly taking orders from Brigadier Lethbridge-Stewart. Aided by Liz Shaw, the Doctor's first task is to investigate a shower of mysterious meteorites which landed in the countryside. The Time Lord discovers that these are no ordinary meteorites: in fact, the plastic-controlling Nestenes have landed, intending to use their automated servants, the Autons, to take over the Earth.
Cambridge scientist Liz Shaw joins UNIT as the Doctor's assistant.
The 
Silurians
The Silurians by Malcolm Hulke, directed by Timothy Combe
UNIT is called in when a nuclear reactor on Wenley Moor starts experiencing strange power disruptions. The Doctor discovers that the activation of the reactor has accidentally awakened the Earth's original civilised inhabitants, the reptilian Silurians, who have lain in suspended animation underground for millennia. Now, the Silurians wish to reclaim their planet, and unleash a deadly virus which will engulf mankind. (Also frequently referred to as Doctor Who and The Silurians. This story has been recolorised, as the original prints are missing.)
The 
Ambassadors Of Death
The Ambassadors Of Death by David Whitaker, directed by Michael Ferguson
When a manned mission to Mars returns to Earth, it soon becomes apparent that the three beings who disembark are not the ship's astronauts. The Doctor realises that the crew have made contact with an alien force on the Red Planet, but his investigations are interrupted when the aliens masquerading as the astronauts are kidnapped by someone who knows them of old. (Episode one is retained in its original color, while episodes two to seven have been recolorised, as the original prints are missing.)
Inferno
Inferno by Don Houghton, directed by Douglas Camfield and Barry Letts
Project Inferno is designed to drill down through the Earth's core, where it will release a powerful new energy source called Stahlman's Gas, named after the project's director. But the Doctor realises that unleashing Stahlman's Gas will have horrible consequences for the planet, and indeed his fears are confirmed when a substance oozing up from the drill shaft begins mutating men into bestial Primords. Before the Doctor can do anything to stop Stahlman, however, a power surge in the TARDIS console sends him to a hostile parallel universe where Project Inferno is nearing completion.
Liz leaves UNIT to return to Cambridge.

Making History

The start of the Pertwee era saw a number of changes to Doctor Who's format. With the Doctor now exiled to Earth, it meant that money could be saved by setting each serial primarily on modern-day Earth, with several recurring motifs. Furthermore, for the first time Doctor Who would be made in colour, despite the fact that it would be several years before the majority of British homes owned a colour TV set. Given all this change, it was felt that Season Seven was the perfect time to retarget Doctor Who away from very young children and more toward teenagers and even adults. As a result, Doctor Who became a more mature, adventure-oriented programme featuring heavier doses of horror and violence.

Season Eight (1971): Enter -- The Master

Companions and Recurring Characters

Josephine (Jo) Grant was the Doctor's assistant during his tenure as UNIT's scientific advisor.

Katy Manning played Jo from Terror Of The Autons in January 1971 to The Green Death in June 1973. She returned in Death Of The Doctor, one of The Sarah Jane Adventures.

Jo Grant

Captain Mike Yates of UNIT was Brigadier Lethbridge-Stewart's second-in-command for much of the Doctor's exile to Earth.

Richard Franklin played Yates on a recurring basis from Terror Of The Autons in January 1971 to Planet Of The Spiders in June 1974. He returned for The Five Doctors in November 1983 and for Dimensions In Time in November 1993.

Captain Yates

The Master was a renegade Time Lord driven by a thirst for power at any cost.

Roger Delgado played the Master on a recurring basis from Terror Of The Autons in January 1971 to Frontier In Space in March 1973.

The Master

The Stories
Terror Of 
The Autons
Terror Of The Autons by Robert Holmes, directed by Barry Letts
The Doctor is warned of a new threat to the Earth: the evil renegade Time Lord known as the Master has arrived. The Master has allied himself with the Nestene Consciousness and has once again paved the way for an Auton presence on Earth. The Doctor and his new assistant, Jo Grant, must stop the Nestenes for a second time -- but this time with the knowledge that the Doctor is going head to head with a being who is quite possibly his true equal. (This story has been recolorised, as the original prints are missing.)
Jo Grant joins UNIT as the Doctor's new assistant.
The Mind Of 
Evil
The Mind Of Evil by Don Houghton, directed by Timothy Combe
The Master, posing as Professor Keller, has created a device he purports will remove the negative impulses from the brains of convicted criminals. The Keller Machine in fact contains an alien mind parasite which turns the convicts into servants of the Master. With their help, the evil Time Lord hijacks a nerve missile, with which he intends to hold a world peace conference hostage. (This story is only available in black and white as the original prints are missing.)
The Claws Of 
Axos
The Claws Of Axos by Bob Baker and Dave Martin, directed by Michael Ferguson
Beings from space arrive in England, calling themselves Axons. They bring with them a fantastic substance called Axonite which can affect the structure of matter. The Axons offer to exchange the Axonite with the various world powers, but the Doctor discovers there is something sinister about the aliens -- not the least of which is their secret allegiance with the Master.
Colony In 
Space
Colony In Space by Malcolm Hulke, directed by Michael Briant
The Time Lords send the Doctor and Jo to an Earth colony in the 25th century. There, the time travellers discover the colonists being ravaged by a weird dinosaur-like beast while sinister miners try to force them to abandon the planet. Meanwhile, the Master has also arrived, searching for a legendary doomsday device believed to be buried in the ruins on the outskirts of the colony.
The 
Daemons
The Daemons by Guy Leopold, directed by Christopher Barry
The Master poses as the new vicar in the rural community of Devil's End, just as an archaeologist begins work on opening an ancient barrow near the village. Despite the Doctor's attempts to stop the work, a Daemon named Azal is released from dormancy within the barrow. A member of an ancient alien race who guided nascent human life on Earth, Azal has remained behind to judge humanity's worthiness. But the Master will stop at nothing to seize Azal's tremendous power. (This story was recolorised as the original prints are missing.)

Making History

With the arrival of Katy Manning, Richard Franklin and Roger Delgado as Jo Grant, Mike Yates and the Master, respectively, the now-famous UNIT Family was complete. Pertwee-era Doctor Who was really hitting its stride in Season Eight, although even the production team would later admit to having overexposed the Master by having him appear in every story that year.

Season Nine (1972): A Galactic Yo-Yo

The Stories
Day Of The 
Daleks
Day Of The Daleks by Louis Marks, directed by Paul Bernard
The Doctor is alerted to a disturbance in the time stream when guerrillas from the 22nd century appear. Their goal is to assassinate Sir Reginald Styles, who is about to host an important international peace conference. The Doctor learns that Styles is destined to blow up the conference, instigating World War Three. As a result, Earth two hundred years in the future is dominated by one race: the Daleks, aided by their brutish footsoldiers, the Ogrons.
The 
Curse Of Peladon
The Curse Of Peladon by Brian Hayles, directed by Lennie Mayne
The Doctor and Jo are sent by the Time Lords to Peladon, a planet attempting join the interstellar Federation. Someone is sabotaging the negotiations, however, and the Doctor suspects it is the Ice Warrior delegates. But as the mystery deepens and the body count mount, the Doctor may prove to be disastrously mistaken.
The Sea 
Devils
The Sea Devils by Malcolm Hulke, directed by Michael Briant
The Master escapes from incarceration and allies himself with the newly-awakened Sea Devils, the aquatic cousins of the Silurians, who have also lain dormant for aeons in suspended animation. With an army of Sea Devils at the Master's command as he seeks to conquer the Earth, the Doctor soon realises that even with the backing of the British navy, there may be no stopping his arch-foe this time.
The 
Mutants
The Mutants by Bob Baker and Dave Martin, directed by Christopher Barry
The Time Lords send the Doctor and Jo to the planet Solos in the dying days of Earth's decadent intergalactic Empire. An Earth delegation, led by the maniacal Marshal, has arrived on Solos, seeking to convert its atmosphere into one more suitable for habitation by humans. The native Solonians oppose this, but at the same time they discover that a crippling plague has befallen their people, turning them into hideously mutated monsters.
The Time 
Monster
The Time Monster by Robert Sloman, directed by Paul Bernard
The Master, posing as Professor Thascalos, obtains the Crystal of Kronos, a relic of ancient Atlantis. Using the Crystal, the evil Time Lord summons Kronos, a powerful Chronovore native to the time vortex. The Doctor pursues his enemy back in time to Atlantis, where he has one last chance to stop the Master from gaining permanent control over Kronos, and unleashing the unstoppable force onto the world.

Making History

Day Of The Daleks saw the first appearance of the Daleks as primary villains in a story in more than four years. During this time, their creator, Terry Nation, had been engaged in unsuccessful attempts to sell the concept of a Dalek television series in the United States.

Season Ten (1972-73): A Return To Wandering

The Stories
The Three 
Doctors
The Three Doctors by Bob Baker and Dave Martin, directed by Lennie Mayne
The Time Lords' energy is being drained through a black hole, so all three Doctors are summoned to investigate. While the First Doctor advises them from the TARDIS scanner, the Second and Third Doctors travel through the black hole. They discover that Omega, a long-lost pioneer of Time Lord history, is imprisoned therein. Believing he has been abandoned, Omega -- now wielding supreme power over the anti-matter universe within the black hole -- is determined to destroy the Time Lords, and force the Doctors to remain within the black hole in his place.
Carnival Of 
Monsters
Carnival Of Monsters by Robert Holmes, directed by Barry Letts
With the Doctor once again free to wander in time and space, the TARDIS brings him and Jo to a cargo ship. The Doctor believes it is the 1920s, until he learns that the boat is one which history records as having disappeared without a trace. It soon becomes clear that they are in fact trapped within an outlawed Miniscope, which holds prisoner a menagerie of oblivious creatures from across time and space.
Frontier In 
Space
Frontier In Space by Malcolm Hulke, directed by Paul Bernard
The Earth Federation is on the brink of war with the rival Draconian Empire. When the Doctor and Jo arrive, they discover someone is trying to inflame the tensions between the two space powers. They quickly learn that the culprit is the Master, but before they can deal with him, the evil Time Lord has them framed as Draconian spies. Worse still, the Master is not working alone...
Planet Of 
The Daleks
Planet Of The Daleks by Terry Nation, directed by David Maloney
The TARDIS materialises on Spiridon, where the Doctor and Jo are aware a Dalek plot is afoot. Teaming up with a band of Thals, the time travellers soon discover an enormous army of Daleks is present on the planet. To make matters worse, a Dalek scientific team is on the verge of gifting their siblings with the invisibility powers of the Spiridon natives.
The Green 
Death
The Green Death by Robert Sloman, directed by Michael Briant
Waste from a chemical plant, Global Chemicals, in Wales has mutated the local insects, turning them into deadly giant monsters. With the aid of a team of local ecologists, the Doctor and Jo set about stopping the monsters and the environmental destruction being wrought by the refinery. But when Mike Yates goes in undercover, he discovers that Global Chemicals' director is not just unscrupulous: he's inhuman.
Jo leaves UNIT to marry ecologist Professor Clifford Jones.

Making History

For the tenth season of Doctor Who, it was clear that something special should be done. As a result, all three Doctors -- William Hartnell, Patrick Troughton, and Jon Pertwee -- were reunited in a celebratory adventure. Hartnell's role had to be minimised due to his ongoing health problems, from which he would sadly pass away just two years later.

Meanwhile, in the midst of the tenth-anniversary jubilation, tragedy struck when the Master, Roger Delgado, was killed in an automobile accident in Turkey. This, combined with Katy Manning's decision to leave Doctor Who, began the dissolution of the UNIT Family and heralded the beginning of the end of the Pertwee era.

Season Eleven (1973-74): Facing Fears

Companions and Recurring Characters

Sarah Jane Smith was a journalist who stowed away aboard the TARDIS during an investigation. Even after leaving the Doctor, she continued defending Earth from alien invasion with the help of several teenagers and the robot dog K·9.

Elisabeth Sladen played Sarah from The Time Warrior in December 1973 to The Hand Of Fear in October 1976. She returned for The Five Doctors in November 1983, Dimensions In Time in November 1993, School Reunion in April 2006, The Stolen Earth / Journey's End in June/July 2008, and The End Of Time in January 2010. She died in April 2011.

Sarah Jane Smith

The Stories
The Time 
Warrior
The Time Warrior by Robert Holmes, directed by Alan Bromly
UNIT is called in when scientists begin disappearing and, with the help of journalist Sarah Jane Smith, the Doctor discovers they are being abducted into the past. Travelling to the Middle Ages, the Doctor learns that a Sontaran, Linx, has crashlanded on the planet and allied himself with a cutthroat brigand named Irongron, who has been using Linx's alien weaponry to terrorise the countryside.
Sarah Jane decides to accompany the Doctor.
Invasion Of 
The Dinosaurs
Invasion Of The Dinosaurs by Malcolm Hulke, directed by Paddy Russell
When the Doctor and Sarah Jane return to modern-day England, they find London deserted and dinosaurs on the loose. It transpires that a group of politicians and scientists are trying to right what they perceive as the cause of all our planet's wrongs by reverting the Earth to a pre-technological level. To make matters worse, they have help -- from inside UNIT and amongst the Doctor's closest friends. (Episode one of this story exists only in black and white as the original print is missing.)
Death To The 
Daleks
Death To The Daleks by Terry Nation, directed by Michael Briant
Two ships -- one piloted by Daleks, the other by a team of humans -- crashlands on Exxilon. Both groups have come to Exxilon in search of the mineral parrinium, the only cure for a space plague which is wreaking havoc throughout the cosmos. The Doctor and Sarah discover that both parties have been mysteriously rendered powerless, meaning that the Daleks' weapons are inoperable -- and they have begun acting unusually cooperative as a result. As his oldest foes begin to show their true colours, however, the Doctor must brave the dangers of the lost city of the Exxilons in order to deliver the parrinium into the rightful hands.

The Monster 
Of Peladon
The Monster Of Peladon by Brian Hayles, directed by Lennie Mayne
The TARDIS returns to Peladon fifty years after its first visit, and the Doctor and Sarah Jane find the planet in disorder once again. The Federation desperately needs trisilicate -- in which Peladon is rich -- in order to wage a war against the oppressive Galaxy Five. But this has lead to claims amongst the natives of Peladon that the Federation is raping their planet. To make matters worse, the ghost of Aggedor, the Sacred Beast of Peladon, has been appearing, apparently condemning the Federation. Once again it seems as if the Ice Warriors are to blame. Can the Doctor be wrong twice?
Planet Of 
The Spiders
Planet Of The Spiders by Robert Sloman, directed by Barry Letts
Mutant Spiders rule the planet Metebelis Three in the far future, holding a regressive Earth colony in a grip of fear. The leader of the Spiders, the mammoth Great One, is constructing a device using Metebelis' powerful blue crystals which will increase her mental powers a millionfold. But the Doctor is in possession of the last crystal, and soon he and Sarah find themselves pursued by the Spiders and their human agents.
Suffering from fatal radiation poisoning, the Doctor regenerates into his fourth incarnation.

Making History

With Richard Franklin leaving Doctor Who this season, and Barry Letts and Terrance Dicks finally prepared to dissolve the long-standing production team, Jon Pertwee himself decided to leave the series, a decision also mitigated by an unwillingness by the BBC to increase the actor's salary. As a result, perhaps the most stable era of the show's history ended on a high note, with the programme's popularity still soaring. But the heights Doctor Who had reached thus far were nothing compared to those it would soon attain...