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 he was embarked upon at the time.

First 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
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
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	while posing as an Adjudicator	Colony in Space	Anagram of Master Gunnjir (gunnjir is the spear of Odin, head of the Norse pantheon)
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
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
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
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.
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 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.
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		The End of the Line
Alan Campbell		Prisoners of Time
Dr. Howard Chithros		Stop the Pigeon
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
Richard		Forgotten
Don Maestro	Whilst trapped on Earth in the 20th century.	Mastermind	Italian for master in the sense of teacher
Dook Domini	In 1931	Mastermind	Named after The Duke of Dominoes, a trump card in an old Wallarian game of chance which beat all other suits.
Alien Artefact Alpha 1	While being kept in the Vault.	Mastermind

"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

"Yana" incarnation

Alias	When used	Story	Etymology
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. The Anglo-Saxons were invading England during the reign of King Arthur.
Razor	used while on board a Mondasian colony ship	World Enough and Time	The Old English word for knife is seax, which is what the name Saxon originated from.

"Missy" incarnation

Alias	When used	Story	Etymology
Missy	New name adopted 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
Doctor Who	When practicing being good aboard a Mondasian colony ship	World Enough and Time

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".