The character's full name is Bruce Gerhardt, as revealed by The Novel of the Film.
Talk about it here.
Bruce Gerhardt was an ambulance EMT in San Francisco in 1999 whom the Master possessed and, in effect, killed. He was described by his wife as "a career, someone who would inconvenience himself without a thought if it would help someone else." (PROSE: The Novel of the Film)
In 1985, Bruce became a paramedic. He was married at some point, but had divorced from his wife by 1994. Shortly afterwards, he struck up a friendship with Miranda while he helped her after a car accident. The pair were soon married. (PROSE: The Novel of the Film)
On 30 December 1999, Bruce helped transport the Seventh Doctor and Chang Lee to Walker General Hospital after the Doctor's gunshot injury. He also unknowingly took the Master — in the form of a Deathworm Morphant — home with him.
That night, while Bruce lay in bed snoring, the Master possessed his body, (TV: Doctor Who) killing Bruce in the process. (PROSE: The Novel of the Film) One of the Master-possessed Bruce's first actions was to kill Miranda, after which he set off in pursuit of the Doctor's TARDIS and the Eye of Harmony within it. After a shaky start, the Master soon mastered Bruce's body, which eventually began to decay. He also adopted Bruce's American accent. (TV: Doctor Who)
Body's fate Edit
The Master, still in Bruce's body, was eventually sucked into the Eye of Harmony in the Doctor's TARDIS. (TV: Doctor Who) As the Eye of Harmony tried to break Bruce's body down into pure energy, the Master managed to ride the energy into a spare room, which the Doctor's TARDIS then ejected into the Time Vortex to protect the Doctor. The Master would remain stranded in Bruce's body for many years. (AUDIO: The Lifeboat and the Deathboat, Day of the Master) As a result of inhabiting Bruce's body, the Master found that he now lacked the mental defences he possessed prior, (AUDIO: The Lifeboat and the Deathboat) and the Ravenous had no interest in consuming him. (AUDIO: Day of the Master)
After the Master was sucked back into the Eye of Harmony, (AUDIO: Planet of Dust) Bruce's body was slowly destroyed, and the Master was only saved by the intervention of Esterath, who deposited him into the body of a deceased vagabond, completely destroying Bruce's body in the process. (COMIC: The Glorious Dead)