As we await the return of Missy/the Master in the opening two-part story of Doctor Who Series 9, and ponder just what grand scheme she will be up to this time, lets prepare ourselves by having a look at some of his/her alternative/unspecified incarnations!
The Second Doctor first encounters one in The Nameless City - this Master is posing as an elderly bookseller by the name of Professor Thascalos. He engineers for a gang of thugs to stage an attack on him, witnessed by Jamie McCrimmon- who thwarts it & earns a gift from the Professor......
Unwittingly, Jamie's laid hands on the Necronomicon as part of a bigger scheme. The Archons, last of the Great Old Ones- a link to the works of HP Lovecraft, creator of the Necronomicon & Cthulhu Mythos- want revenge on the Time Lords for declaring war on them & stealing the 'seeds' necessary to grow TARDISes from them in the early days of the Rassilon Era on Gallifrey, wiping out all but seven of them & they've found an ally in the Master! They need a TARDIS to transport themselves from their nameless city to right the perceived wrong- hence the title, which is borrowed from an HP Lovecraft story. You might by now have guessed that a certain police box is their target. Rather poetically its music that saves the day, as the dream team of the Doctor & Jamie put their recorder & bagpipes respectively to good use in disturbing the musica universalis or music of the spheres that the Archons move in time to. Have a look at some of Pythagoras's theorems, or consider this quote from Elizabeth Clare:
"The study of geometry, which descends to us from Pythagoras, is a meditation on the harmony of the cosmic order, and it is a meditation upon music. If you meditate upon geometry instead of just learning it in a linear way, you can actually hear the music of the spheres, because the geometric forms will key the eye and the ear to the inner sound. Every line that you draw you have the carry-over from the spiritual octaves to the physical."Or, as Johannes Kepler put it:
"The heavenly motions... are nothing but a continuous song for several voices, perceived not by the ear but by the intellect, a figured music which sets landmarks in the immeasurable flow of time."
A little later in an alternative time-line, another Master appears alongside that universe's Third Doctor in Sympathy For The Devil, portrayed by Mark Gatiss- writer of episode including The Unquiet Dead, The Idiot's Lantern & Victory Of The Daleks. It just so happens that this Master finds himself on Earth in 1997 during the handover of Hong Kong into Chinese governance. He'd worked for the United Nations until defecting to the side of the Chinese, & now assumes the alias of ' Ke Le', using brainwashed political prisoners as soldiers ( by means of an alien parasite) as ' Ke Le Divisions'.
The Doctor's kept him waiting- though he was supposed to begin his 'Earth exile' in 1970 ( since which time the Master has been on Earth ), he only arrives in 1997!
Another jump forward in time to First Frontier, which reveals that the Master has managed to cure himself of the 'Cheetah Virus' which was troubling him in Survival thanks to a deal with the Tzun, who asked for his help in mounting an invasion of Earth in return for the use of their genetic engineering technology to rid himself of what ails him. Shortly after returning to his proper Time Lord biological form, he's shot by Ace & regenerates into a form said to resemble Basil Rathbone. This Master also appears in Happy Endings prior to another change of face.....which could have resulted in the Master who appears in the 'trial' flashback at the beginning of the 1996 Eighth Doctor TV movie, sentenced to death.
In the Eighth Doctor Adventures novel The Adventuress Of Henrietta Street, a character known only as the ' Man with the Rosette' features, & is heavily implied to be another Master. He attends the Doctor's wedding to Scarlette, the titular Adventuress, having first met her in an 18th century pub- leaving before the Doctor arrives. He acts as ringbearer in a sense, giving her two rings in a later meeting at London's docks, & attends her marriage- a ceremony intended to bind the Doctor into the protection of Earth, but is also hinted to reflect the romantic feelings of both parties- leaving a wedding present of a single fake rose. He later appears to the Doctor in a vision during The Gallifrey Chronicles, the 73rd & final Eighth Doctor Adventure.............
Alex Macqueen was given the Masterly mantle in the UNIT- Dominion series from Big Finish Audio-given a new cycle of regenerations by the Time Lords after being resurrected to fight in the Time War! This bald besuited incarnation has his own agenda, though- wanting to take control of the Eminence & by extension its army of Infinite Warriors- those who had been possessed by it. This quest begins during Dominion, during which he's initially impersonating the Doctor- who's then in his Seventh incarnation- before revealing himself & his true nature.
By Dark Eyes 2 (comprising The Traitor, The White Room, Time's Horizon & Eyes Of The Master) he's after the Eighth Doctor's companion Molly O'Sullivan & her ' dark eyes' which are caused by retro-genitor particles- a form of radiation so deadly it can stop Time Lords regenerating. Perhaps altogether more interesting is The Infinity Doctors, set in another alternate universe in which the Master isn't a villain even in the slightest- here, he's called the Magistrate & serves as the highest legal authority on Gallifrey. And who's his oldest friend? It's the Doctor, who's in an unspecified incarnation!
This Master wears black & has a goatee, and his obsession with law & order eventually threatens to lead him down a dark path........well, it wouldn't be the same otherwise would it?..