Aliases of the Master

Like the Doctor, the renegade Time Lord known as the Master used many aliases. However, while the Doctor used false names on a fairly ad hoc basis to avoid awkward questions, the Master usually adopted them in order to further whatever scheme they were embarked upon at the time.

"The Master" was itself an alias. He chose this name, as the First Doctor did his, while attending the Academy. (TV: The Sound of Drums; AUDIO: The Destination Wars)

"Renegade" incarnation

Alias	When used	Story	Etymology
The Inventor	when posing as a hero on the planet Destination	The Destination Wars

"UNIT enemy" incarnation

Alias	When used	Story	Etymology
Koschei	An old name the Master used while at Time Lord Academy, he resumed using it again sometime after he left Gallifrey	Divided Loyalties The Dark Path	In Russian folklore, Koschei hides his soul in an obscure location under many layers of protection so that he can never die.
Professor Carl Thascalos	to give Jamie McCrimmon the Necronomicon, and to gain access to facilities of the Newton Institute	The Nameless City The Time Monster	Greek for master, pointed out by Jo Grant
Colonel Masters	to infiltrate Rex Farrel's plastics company	Terror of the Autons	His typical alias with an s on the end
Emil Keller	assumed identity of the creator of the Keller Machine	The Mind of Evil	Emil is derived from the Latin word aemulus, meaning rival, and Keller is derived from Old English cwellere, meaning executioner
Martin Jurgens	Martin Jurgens is the Adjudicator whose credentials the Master stole.	Colony in Space	A coincidental anagram of Master Gunnjir (gunnjir is the spear of Odin, head of the Norse pantheon) "Martin Jurgen" in the novelisation
Victor Magister	to insinuate himself socially into the Devil's End community as a vicar, and later the name used when being charged for his crimes	The Dæmons Who Killed Kennedy	Latin for master
Conran		The Man in the Ion Mask
Prisoner M		Harvest of Time	The first letter of his typical alias
Jack Harris	to use a stolen Ford Cortina to reach his TARDIS	The Eight Doctors	Name of car's original owner whom the Master had killed
Brigadier Lethbridge-Stewart	to trick Sergeant Benton, and later the Third Doctor and Jo Grant	The Time Monster The Heralds of Destruction
Frey	whilst in Sweden, 141	The Spear of Destiny	Old Norse for master
General Mayhew		The Heralds of Destruction
Inspector LeMaitre	to infiltrate a village fete by pretending to be a police inspector from Scotland Yard	Inspector !Last of the Gaderene	French for the master
Dook Domini	In the 1930s	The Duke of Dominoes	Named after The Duke of Dominoes, a trump card in an old Wallarian game of chance which beat all other suits.
Senator Szef		The Seismologist's Story	Polish for boss, chief
McMaster		Doctor Who Fights Masterplan "Q"
Geoffrey Thynne	to infiltrate Kenstone Hall	The Touch of the Nurazh
Aloysius Fischer	to infiltrate a UNIT Christmas party	UNIT Christmas Parties: Christmas Truce	Dr. Aloysius Fischer was the person the Master assumed the identity of, though he assures the Doctor that Fischer is still alive. Aloysius is originally derived from the German name Chlodovech, meaning famous in war.
The Raffolite Ambassador		The Same Face
Duke Dominus	to impersonate a 1930s Chicago gangster	The Duke of Dominoes	Dominus from the Latin for lord or master of the house
Rupert Masters	Claiming to represent the "Masters Corporation"	Night Flight to Nowhere
The Doctor		Anything You Can Do
The Commissioner of Sirius IV		Frontier in Space
Estro	while posing as an adviser to Lord Haldoran in an effort to procure a Dalek matter transmuter	Legacy of the Daleks	Esperanto for master
Professor Dominar		Doorway to Hell	Spanish for dominate

Degenerated body

Alias	When used	Story	Etymology
Dr. Damien Scott	Whilst working for the Dominus Institute in the body of a future incarnation.	Vampire of the Mind	In French Damien means to subdue or tame, symbolizing the Master's position in the Dominus Institute.
General Malgrove	Whilst leading a faction of the Gorlan Empire.	The Two Masters	The Gorlan word for master
Van Houten	In the 1890s	Maurice	Named after chocolates common in the time period.
Mr. Dominus	When visiting the Red Tavern in the 1890s	Masterpiece	Dominus from the Latin for lord or master of the house
Mwalimu	while hiding beneath Colonel Spindleton's manor house in 1979	Trail of the White Worm	Swahili for master in the sense of teacher
Interplanetary Police Inspector Efendi	while on Secus	The Evil One	Turkish for "Master"

"Tremas" incarnation

Alias	When used	Story	Etymology
Tremas	to deceive Nyssa on Logopolis after taking over her father's body	Logopolis	A coincidental anagram of "Master"
The Portreeve	to trap the Fifth Doctor in Castrovalva	Castrovalva
Kalid	used to take control of the Xeraphin gestalt	Time-Flight	Kalid derives from the Indian Kalidasa meaning servant of Kali, an Indian goddess of time and change and usually depicted as being dark and violent
Sir Gilles Estram	to avert the signing of the Magna Carta in 1215.	The King's Demons	Estram is a simple anagram, coincidentally the name of a knight whom he impersonates.
Mr. Tase		The Velvet Dark	An anagram of Master
Merlin		The Creation of Camelot
The Sheriff	to gain access to the regenerative fountain near Eternity, California.	A Town Called Eternity
Professor Masterman		The Time Savers
Branko Gospodar	to access the TITAN Array in order to destroy the Chronovores	The Quantum Archangel	Serbo-Croatian and Slovenian for master
Keith Potter	Assumed identity of possessed body as part of a plan to dominate the dimensional nexus.	The End of the Line
Alan Campbell		Prisoners of Time
Dr. Howard Chithros		Stop the Pigeon
Dominus		Crossing the Rubicon
Major Kreer	used when allied with the Tzun in 1950s America.	First Frontier	Continued to use alias after his regeneration

"Tzun" incarnation

Alias	When used	Story	Etymology
Count Marius Castillo		Housewarming

"John Smith" incarnation

Alias	When used	Story	Etymology
Mr. Seta	Used aboard the starship Gallery	Dust Breeding	Anagram of master
Dr. John Smith	Used while amnesiac on an unnamed colony world	Master

While body-jumping

Alias	When used	Story	Etymology
Bruce	Occasionally reverted to impersonation of a San Franciscan paramedic named Bruce after he had taken over Bruce's body	Doctor Who
Daniel	While hiding his true identity from River Song	The Lifeboat and the Deathboat
Brian	Used when talking to Kitty on Kesta	Masterful
Richard	Possessed human	Forgotten
Don Maestro	Whilst trapped on Earth in the 20th century.	Mastermind	Italian for master in the sense of teacher
Alien Artefact Alpha 1	While being kept in the Vault.	Mastermind
The Protector	While on the planet Parrak	Planet of Dust
Jeremy	Whilst under the care of Kitty	Masterful

"Bald" incarnation

Alias	When used	Story	Etymology
Dr. Harcourt De'ath	To practice eye surgery on many patients, in order to literally "have eyes everywhere"	Time's Horizon, Eyes of the Master	Bar the apostrophe, De'ath is spelt the same way as "Death".
Kappa Chi	Designation as CIA agent.	The Death of Hope
Master-Builder	When creating the Dalek Time Controller's new empire.	The Monster of Montmartre
The Doctor	Whilst masquerading as a future incarnation of the Doctor.	Dominion
Michael Masterson	While living in Hexford in the body of a past incarnation.	And You Will Obey Me

"War" incarnation

Alias	When used	Story	Etymology
Mr Orman	While helping the mining process of Callous	The Glittering Prize
Cyber-Master	Whilst masquerading as a Cyberman, superior to the Cyber-Controller.	Master of Worlds
TS Mereath	In 19th century US.	The Coney Island Chameleon	Anagram of "The Master"
Crazlus	Masquerading as Crazlus to Narvin
Sorvad	While pretending to be the late Davros' uncle on Skaro.	The Master's Dalek Plan	Davros spelled backwards. The Master claims this is a "family tradition".
The Doctor	Whilst masquerading as the Doctor on Gardezza.	Beneath the Viscoid
Dr. Keller	Whilst on Arcking.	The Good Master	Reusing alias from The Mind of Evil
Professor Yana	Chameleon arch identity	Utopia	Had no known meaning of its own, but the Face of Boe made up an acronym, "You Are Not Alone".

"Harold Saxon" incarnation

Alias	When used	Story	Etymology
Harold Saxon	used to become Prime Minister of the United Kingdom	The Sound of Drums	Mister Saxon was a coincidental anagram of Master No Six; Harold is a derivative of Old English Hereweald meaning Master of the Armies
Mr. Razor	used while on board a Mondasian colony ship	This World Enough and Time	The Old English word for knife is seax, which is what the name Saxon originated from. His name, then, is ostensibly "Mr. Saxon" - the name given the first time the Saxon incarnation is mentioned in The Christmas Invasion.
Alpha 7	designation for the Mondasian Cybermen created on a colony ship for Operation Exodus	Alit in Underland

"Missy" incarnation

Alias	When used	Story	Etymology
Mrs. Braithwaite	After marrying Bobo Braithwaite	Dismemberment
Missy	New name adopted shortly after regenerating into female form	Deep Breath, Dark Water	Short for "Mistress", feminine form of "Master".
Mobile Intelligence Systems Interface	Ruse allowing close contact with and delaying recognition by the Doctor	Dark Water	Backcronym from "Missy"
Miss Magister	When posing as a teacher	Yes, Missy	Latin for master
Beatrice Foxcroft	When meeting with the Monk, who was disguised as Henry VIII	Divorced, Beheaded, Regenerated	Beatrice means "bringer of joy or blessings", as one would expect a queen to
Doctor Who	When practicing being good aboard a Mondasian colony ship	World Enough and Time

"Spy" incarnation

Alias	When used	Story	Etymology
O	Assumed identity of an MI6 member who he had shrunk with the Tissue Compression Eliminator.	Spyfall	While posing as "O", the Master claimed he was named as such as a joke; whenever "O" met with C, C would exclaim "Oh, God!" After revealing himself, however, he explained that he chose the name for satisfaction, anticipating correctly that the Thirteenth Doctor would exclaim "Oh..." as he dropped the act.
Officer O	Alias used while allied with the Third Reich.	Spyfall Crack Noor's Code

Behind the scenes

• During Anthony Ainley's tenure as the Master, pseudonyms made from anagrams of "Tony Ainley" were often used in the credits — both on-screen and in Radio Times — for the Master's disguises, such as Neil Toynay for the Portreeve in Castrovalva.
• Another, craftier pseudonym was used in Radio Times for The King's Demons, when Sir Gilles was listed as being played by "James Stoker" — an anagram of "Master's Joke".
• In Sympathy for the Devil, Mark Gatiss, who voiced an alternate version of the Master, is credited as "Sam Kisgart", an anagram of the actor's name. When this incarnation of the Master returned in The New Adventures of Bernice Summerfield, Gatiss was again credited as Kisgart but the joke was dropped out for later user stories.
• In the previews of Ascension of the Cybermen, the Spy Master's return for the cliffhanger was foreshadowed by "Barack Stemis" being credited for a character called "Fakout" at the end of the cast-list. "Barak Stemis" is an anagram of "Master is back", while "Fakout" sounds like "fake-out".
• In the DVD commentary for TV: The Sound of Drums, Russell T Davies claims that "Saxon" was an anagram of "Axons", made in reference to TV: The Claws of Axos.
• Professor Stream in The Hollows of Time was originally intended to be a pseudonym of the Master, but copyright restrictions prevented them from making this explicit in the story. "Stream", like "Tremas", is an acronym of "Master". The story is listed as a Master one on the Big Finish website.