The Aztecs is the sixth serial in the British science fiction television series Doctor Who, which was first broadcast on BBC1 in four weekly parts from 23 May to 13 June 1964.

Barbara becomes mistaken for the goddess Yetaxa, and accepts the identity in hope of persuading the Aztecs to give up human sacrifice, despite the Doctor's warnings about changing history.

With the TARDIS trapped in a tomb, Barbara Wright (Jacqueline Hill) is mistaken for a female reincarnation of the ancient high priest Yetaxa, and assumes her guise and identity.

The urgent warnings of the First Doctor (William Hartnell) that Barbara cannot change history fall on deaf ears, much to his fury.

In a pitched battle to gain access to the tomb door, Ian kills Ixta in a fight to the death to protect the TARDIS crew.

Writer John Lucarotti was commissioned to write The Aztecs by script editor David Whitaker on 25 February 1964,[4] while another of his stories—the show's fourth serial, Marco Polo—was in production.

[6] John Crockett was assigned to direct the serial due to his knowledge of history, having previously worked on the fourth episode of Marco Polo.

[7] Designer Barry Newbery found the serial difficult for research, due to the limited information on the Aztecs at the time.

[9] Keith Pyott was chosen for the role of Autloc, the High Priest of the Aztecs, while Ian Cullen and Margot Van der Burgh played Ixta and Cameca, respectively.

After the broadcast of the first episode, Television Today's Bill Edmunds praised the villainous nature of the characters Tlotoxl and Ixta, but felt that Barbara should have "a chance to look beautiful instead of worried".

[21] In The Discontinuity Guide (1995), Paul Cornell, Martin Day, and Keith Topping described the serial as a "lyrical piece of BBC costume drama and a gem to cherish".

[23] In A Critical History of Doctor Who (1999), John Kenneth Muir called The Aztecs "perhaps the best-written of Doctor Who's first-year serials", and Lucarotti's script as "among the best written and best executed stories" of the classic series; he praised the characterisation, tension, and philosophical nature of the script, as well as the central role of Barbara and the performances of Hill, Russell, and Ringham.

[3] In 2008, Radio Times reviewer Mark Braxton called The Aztecs one of the best Doctor Who adventures, highlighting Barbara's dilemma about changing history, the art direction, and the "sense of impending tragedy"; he noted minor issues, such as the backdrops and unconvincing fight scenes.

[25] In 2013, Ian Berriman of SFX described the serial as "Jacqueline Hill's finest hour", but felt that "the show is stolen by John Ringham as Tlotoxl".

[18] Digital Spy's Morgan Jeffrey named it the tenth best Doctor Who story, praising the script, performances and emotional impact of the serial.

Jeffrey summarised the serial as "quite simply 100 minutes of sensational drama – it's William Hartnell's finest hour on Doctor Who and one of the show's very best offerings".