Bob was a Cleric, and a member of Father Octavian's mission to track down the last Weeping Angel, which was on the Byzantium when it crashed. Like the rest of Octavian's clerics, he was given a sacred name in the service of the church. During the expedition in the "Maze of the Dead", he was scolded for showing fear and wasting ammunition on a seemingly harmless statue. The Doctor however encouraged him and told him that his fear would keep him alive.
Bob was killed by a Weeping Angel when it snapped his neck, after luring him in by using the voices of the other clergymen. However, the Doctor could still communicate with Bob through Father Octavian's communication device. He explained that the Angels lack a voice, so it callously stripped Bob of his cerebral cortex and copied his consciousness to use him has a mouthpiece to talk to the Doctor. Bob's consciousness confirmed that, while painful, at least his death "was quick and didn't hurt as much as he thought it would."
Bob's consciousness confirmed the Doctor's suspicion that the crash of the Byzantium was a rescue mission on the Angel's part. While its brethren were still feeding on the ship's temporal core to heal, it was coming for the Doctor and the others, and it would enjoy killing them.
The Angel tried to anger the Doctor by having Bob's consciousness also tell him how his words of encouragement ultimately failed the soldier: he died alone and in fear. The Doctor expressed sincere regret for Bob's death, and promised to what remained of him that he would make the Angels even more sorry for what they had done. (DW: The Time of Angels)
He was later talking to the Doctor about an armada that would be used with the ship's power. He even said comfy chairs which amused the Doctor. Far later, he asked the Doctor to jump into the rift and save everyone else, but when the Doctor forced him and the rest of the Weeping Angels with the gravity, he supposedly disappeared forever. (DW: Flesh and Stone)