Name: Azathoth; real name unknown
Time of Origin: Uncertain; The Doctor encountered its minions on Earth in 1887, but there is evidence that Azathoth’s ‘home planet’ (Or at least the world where it confronted The Doctor) was in another era; it died in San Francisco in 1908.
Doctor; the First Doctor learned about the portal to Azathoth’s world but did not go there himself.
Companions: Ace, Bernice Summerfield; Susan learned about the portal but didnít travel through it personally.
History: While Azathoth was a powerful villain in itself, it is interesting to note that it is one of the few foes The Doctor has encountered where even he is not fully aware of its true nature. Although Azathoth claimed to be one of the Great Old Ones - beings from the previous universe who escaped its destruction and acquired great powers in this one - The Doctor had encountered so many other Old Ones over the course of his lives - including Yog-Sothoth (The Great Intelligence in "The Abominable Snowman") and Hastur the Unspeakable (Fenric in "The Curse of Fenric") - that he quickly identified Azathoth as nothing but a giant mutant slug, concluding that it was trading on the original Azathoth's reputation to make itself appear more imposing to outsiders than it was (Although it was unclear if Azathoth had reached the point where it believed its own propaganda or was just going along with the claim out of habit, as it continued to act as Azathoth even after The Doctor realised the truth).
Having arrived on the planet Ry'leh a long time ago - Ry'leh being a world with a polar ice cap that covered the atmosphere - Azathoth had used its powers to convert various Ry'lehans into its followers, the Rakshassi, named for Hindu demons, who resembled winged armoured crustaceans with billowing leathery wings and thorny growths on their heads in place of eyes, the Rakshassi being fanatically devoted to it due to its mental control. Interestingly enough, because of the relative positions of Earth and Ry'leh in the space-time continuum, it was possible to open a gateway between them if the right words were chanted, although the gateway could only be opened between India and the Plain of Leng on Ry'leh.
During an expedition in India, the explorer Signor Holmes discovered legends of the path between Earth and Ry'leh and the series of chants necessary to open this path, with this discovery being witnessed by the First Doctor and Susan when they were in the same area. Although Signor Holmes did not follow up on his discoveries at the time, the journals in which he wrote about his work were left in the Library of St John the Beheaded, a library containing books that the Vatican regarded as dangerous but did not want to destroy due to their potential value, where they were eventually discovered and read by his eldest son, Sherringford (Thirteen years older than Mycroft and twenty years older than Sherlock, Sherringford managed the family estate while his brothers worked in London). Based on his father's writings, Sherringford managed to recreate the chants that would allow him to travel to Azathoth's world, only to fall under Azathoth's influence and begin his efforts to lead her followers to Earth.
When the Vatican discovered the disappearance of the journals, they called in Sherlock Holmes to investigate the matter as an unofficial agent who could be trusted to remain quiet (Although they did not initially reveal the nature of the stolen books). Guessing that the books had been stolen to prevent him from reading them, the Seventh Doctor - who had recently arrived in that time to consult the journals - contacted Holmes and Watson to offer his assistance in the investigation, despite acknowledging that he was a suspect himself. With The Doctor's companions Bernice Summerfield and Ace assessing the situation in India and on Ry'leh respectively, The Doctor set out to question some of the suspects with Watson, only for one to spontaneously combust during the interview.
Having learned that most of the suspects worked for British Intelligence - as well as serving as members of the Diogenes Club where Mycroft Holmes spent most of his time - The Doctor and Holmes were able to develop further theories about the motive for the thefts. Having confirmed that one member of the club, Baron Maupertuis, was conducting apparent s√©ances to put him in contact with an unknown third party, The Doctor and Holmes met with the elder Holmes brothers to learn what was actually in the journals they were looking for, as well as being introduced to a native of Ry'leh who had come to ask for help. Having stolen one of the journals from Maupertuis, Holmes, Watson and The Doctor headed to India to join Benny and a Diogenes expedition, confronting and defeating their unknown foe's altered human minions; parts of their brains had been removed, which resulted in new parts being activated, providing them with such powers as pyrokinesis, the books having been smuggled out when parts of their bodies were literally hollowed out to provide spaces for them to conceal the books in.
Although the Diogenes expedition were able to interrupt the final ritual and kill Maupertuis, they were unable to stop it before a small army travelled through, forcing the four of them to travel through the portal themselves. Having arrived on Ry'leh, The Doctor, Sherlock and Benny were captured by the natives while Watson was separated from the group, although he was fortunately able to make contact with Ace and learn more about their new world. As Ace and Watson followed their friends, The Doctor, Holmes and Benny learned about Sherringford's new allegiance and the real plan for Ry'leh to invade Earth as he took them to Azathoth, indenting for his 'god' to convert them. Fortunately, Ace was able to use a smart missile she had acquired a while back to keep Azathoth at bay, allowing her and Watson to pose as recent 'converts' - using body parts from a recently killed Rakshassi to give the impression that they were mutating themselves - and be left alone with The Doctor, Benny and Holmes so that they could save their friends.
Although Azathoth was able to 'convert' the smart missile into another follower, The Doctor and his allies were able to escape her presence, subsequently tracking Azathoth's forces as they prepared to open the portal. Based on a comment Ace had overheard, The Doctor learned that a dissonant chord could shift the terminus of the gateway, allowing him to avert the invasion by disrupting the chant with additional sounds so that the portal was redirected to San Francisco at the time of the 1908 earthquake, arriving in a hotel just before it was destroyed by a gas explosion when a resident attempted to use the kitchens after the initial earthquake had passed. As Azathoth and her forces burned to death, Sherringford attempted to strangle Watson for contributing to the death of his god, but Holmes intervened, killing his brother to save his friend. With the threat eliminated, The Doctor returned to London to recover the TARDIS from where he had left it, subsequently returning to San Francisco mere moments after he had departed from his friends' perspective, taking Holmes and Watson home before he, Benny and Ace resumed their travels.