This season was a season of major changes for Doctor Who, including some that have influenced the series and franchise ever since. Most notably, season 4 saw William Hartnell's First Doctor hand off the baton to Patrick Troughton's Second Doctor in the very first regeneration. When Hartnell announced his plans to leave the series, the show's writers came up with the idea of having the Doctor change his appearance and personality. In 1966, while it was not uncommon for actors to change in ongoing TV and film roles, this was possibly the first time a change in appearance was written into the very nature of the character.

Season 4 Episode 9 - The Power of the Daleks (1)

The TARDIS arrives on the Earth colony of Vulcan where the newly-regenerated Doctor assumes the identity of an Earth Examiner. Air Date : 5th-Nov-1966

Season 4 Episode 1 - The Smugglers (1)

The Doctor discovers Polly and Ben aboard the TARDIS shortly before the ship arrives in 17th century Cornwall, where the local churchwarden gives the Doctor a cryptic message shortly before being murdered. Air Date : 10th-Sep-1966  Read More

Season 4 Episode 2 - The Smugglers (2)

Pike is convinced that the Doctor knows the location of Avery's treasure while Polly and Ben try to convince the locals they were not responsible for Longfoot's murder. Air Date : 17th-Sep-1966  Read More

Season 4 Episode 3 - The Smugglers (3)

Polly and Ben are placed in the custody of Blake, who reveals he also has his suspicions about the Squire, while the Doctor and Kewper are forced to team up to escape from Pike's ship. Air Date : 24th-Sep-1966  Read More

Season 4 Episode 4 - The Smugglers (4)

The Doctor and his friends are at the mercy of Cherub, who is now seeking Avery's treasure for himself, while Pike prepares to attack the village. Air Date : 1st-Oct-1966  Read More

Season 4 Episode 5 - The Tenth Planet (1)

In 1986 a new planet appears in the Solar System which turns out to be a long-lost twin of Earth's named Mondas. Its inhabitants are the Cybermen. Air Date : 8th-Oct-1966  Read More

Season 4 Episode 6 - The Tenth Planet (2)

The Doctor's warnings are ignored and the Cybermen take over the base, hampering the crew's efforts to help Zeus IV. Air Date : 15th-Oct-1966  Read More

Season 4 Episode 7 - The Tenth Planet (3)

With the Doctor out of action, it is up to Polly, Ben and Barclay to stop Cutler using the Z-Bomb and devastating half the world. Air Date : 22nd-Oct-1966  Read More

Season 4 Episode 8 - The Tenth Planet (4)

The Cybermen take over the base again, apparently to stop the humans using the Z-Bomb, but then the Doctor realises they intend to use it themselves to destroy Earth. Air Date : 29th-Oct-1966  Read More

Season 4 Episode 9 - The Power of the Daleks (1)

The TARDIS arrives on the Earth colony of Vulcan where the newly-regenerated Doctor assumes the identity of an Earth Examiner. Air Date : 5th-Nov-1966  Read More

Season 4 Episode 10 - The Power of the Daleks (2)

While the Doctor worries about the inert Daleks in the capsules, Lesterson makes plan to reactivate one of them. Air Date : 12th-Nov-1966  Read More

Season 4 Episode 11 - The Power of the Daleks (3)

The Doctor fails to convince the colonists of the danger posed by the Daleks and soon the other two are also reactivated. Air Date : 19th-Nov-1966  Read More

Season 4 Episode 12 - The Power of the Daleks (4)

With Polly being held prisoner by the rebels, the Doctor and Ben decide to investigate them, while Lesterson discovers the Daleks are reproducing. Air Date : 26th-Nov-1966  Read More

Season 4 Episode 13 - The Power of the Daleks (5)

The Doctor and Quinn attempt to escape in order to stop Bragen using the Daleks to take over the colony. Air Date : 3rd-Dec-1966  Read More

Season 4 Episode 14 - The Power of the Daleks (6)

With Bragen having taken over, the Daleks trick the rebels into turning them loose and only the Doctor can stop them wiping out the entire colony. Air Date : 10th-Dec-1966  Read More

Season 4 Episode 15 - The Highlanders (1)

The Doctor, Polly and Ben arrive in 1746, in the aftermath of the Battle of Culloden, and are captured by a group of Highlanders shortly before they themselves are captured by redcoats. Air Date : 17th-Dec-1966  Read More

Season 4 Episode 16 - The Highlanders (2)

Polly and Kirsty capture Lieutenant Ffinch to try and enlist his help while the Doctor tricks Grey in order to escape. Air Date : 24th-Dec-1966  Read More

Season 4 Episode 17 - The Highlanders (3)

With the Highlanders imprisoned aboard Trask's ship, the Doctor attempts to expose Grey's plan. Air Date : 31st-Dec-1966  Read More

Season 4 Episode 18 - The Highlanders (4)

Ben manages to join up with the Doctor, Polly and Kirsty and together they work to free the Highlanders from Trask's ship before Grey sells them into slavery. Air Date : 7th-Jan-1967  Read More

Season 4 Episode 19 - The Underwater Menace (1)

The TARDIS materialises on a deserted beach where the Doctor and his friends are captured by primitive warriors and taken to the fabled city of Atlantis. Air Date : 14th-Jan-1967  Read More

Season 4 Episode 20 - The Underwater Menace (2)

While Ara tries to save Polly from being turned into a Fish Person and Ben and Jamie try to escape from the mines, the Doctor discovers the full extent of Zaroff's plans. Air Date : 21st-Jan-1967  Read More

Season 4 Episode 21 - The Underwater Menace (3)

The Doctor and Ramo are sentenced to be sacrificed to the goddess Amdo and must escape to put a stop to Zaroff's plan. Air Date : 28th-Jan-1967  Read More

Season 4 Episode 22 - The Underwater Menace (4)

With Zaroff's plan nearing completion, the Doctor and Ben realise the only way to save the world is to destroy Atlantis. Air Date : 4th-Feb-1967  Read More

Season 4 Episode 23 - The Moonbase (1)

The TARDIS arrives on the Moon in the year 2070.When Jamie is injured, the other travellers are forced to seek the help of a moonbase afflicted with a space plague. Air Date : 11th-Feb-1967  Read More

Season 4 Episode 24 - The Moonbase (2)

The Doctor and his friends attempt to convince the Moonbase crew that the Cybermen are responsible for the disappearances and find a cure for the plague. Air Date : 18th-Feb-1967  Read More

Season 4 Episode 25 - The Moonbase (3)

The Cybermen take over the Moonbase and begin using the Gravitron to attack Earth but Polly, Ben and Jamie come up with a way to fight back. Air Date : 25th-Feb-1967  Read More

Season 4 Episode 26 - The Moonbase (4)

With the Cybermen preparing to launch a full attack, the Doctor and his friends must keep the Moonbase and the Gravitron out of their hands until help arrives from Earth. Air Date : 4th-Mar-1967  Read More

Season 4 Episode 27 - The Macra Terror (1)

The TARDIS arrives at a holiday camp company with the crew worried by a prediction of giant crabs and the Doctor becomes interested in the apparent madman Medok's stories of creatures that roam the colony at night. Air Date : 11th-Mar-1967  Read More

Season 4 Episode 28 - The Macra Terror (2)

The Doctor is unable to convince the colonists that the Macra exist and an attempt to brainwash his companions results in Ben betraying his friends. Air Date : 18th-Mar-1967  Read More

Season 4 Episode 29 - The Macra Terror (3)

The Doctor, Polly and Jamie are sentenced to work in the pits and an escape attempt sees Ben's loyalties called into question again. Air Date : 25th-Mar-1967  Read More

Season 4 Episode 30 - The Macra Terror (4)

The Doctor and Polly manage to save Jamie from the Macra and then try to show the Pilot who is really in charge of the colony. Air Date : 1st-Apr-1967  Read More

Season 4 Episode 31 - The Faceless Ones (1)

The TARDIS materialises on the runway of Gatwick Airport, where Polly witnesses a murder only to be kidnapped before she can report it. Air Date : 8th-Apr-1967  Read More