Victor Magister
Victor Magister was an alias which was adopted by the Master as he operated on 20th century Earth. The Third Doctor noted his use of the surname "Magister", the Latin word for "master".
History
In the village of Devil's End, the Master posed as a parish priest from Cyprus named "Victor Magister" (TV: The Dæmons; PROSE: Who Killed Kennedy) after murdering the old vicar, Canon Smallwood, with his Tissue Compression Eliminator and burying his shrunken body in the churchyard. (PROSE: The Eight Doctors)
The Master proceeded to summon the ancient Dæmon Azal, but he failed to understand the power and control that was necessary following summoning him. Following Azal's confrontation with Jo Grant's selflessness, Azal destroyed himself through Jo's illogical actions. The Master was captured by UNIT following a failed attempt to escape in the Third Doctor's car, Bessie. (TV: The Dæmons)
At his trial, the government used the Master, under the name "Victor Magister", as a scapegoat for all the alien attacks which had recently occurred. (PROSE: Who Killed Kennedy)
In the late 2010s, the alias Magister1971 was used by an individual who sold P.R.O.B.E. director Giles a fake DVD copy of the lost Doctor X episode Doctor X and the Caverns of Andostar. (WC: Doctor X)