Bruce Gerhardt

Bruce was an ambulance driver in 1999 San Francisco. He helped transport the Doctor and Chang Lee to a hospital after the Doctor's gunshot injury. He also unknowingly took the Master (in the form of a Deathworm or Morphant) home with him. That night, while he lay in bed snoring (much to the annoyance of his significant other, Miranda), the Master possessed his body, presumably destroying Bruce's consciousness in the process. One of the Master-possessed Bruce's first actions was to kill Miranda, after which he set off in pursuit of the TARDIS and the Eye of Harmony within. After a shaky start, the Master soon mastered Bruce's body, although Bruce's body began to decay. He also adopted Bruce's American accent.

Bruce's body was eventually sucked into the Eye of Harmony in the Doctor's TARDIS and, presumably, destroyed. (DW: Doctor Who)

The Master's consciousness, however, was later resurrected by the Time Lords and given a new physical form in order to fight in the Last Great Time War. (DWM: The Fallen, DW: Utopia)

Behind the scenes
Bruce's last name is never revealed in the film, although the novelisation contains an introductory scene which may have been scripted, but cut from the final film. In this scene, police arrive to investigate the Doctor's shooting, and interview Chang Lee long enough to figure out that he should accompany the victim to the hospital. They introduce Lee to Bruce, who responds by saying his name is "Bruce Gerhardt".