Mook Jayasundera

 was a friend of Mickey Smith and a member of his Bad Wolf band. He was a "shy, tiny lad with big staring eyes".

Mook was a son of Mrs Jayasundera and the youngest of six brothers. He stayed at Mickey's house so he could "gradually, cautiously, definitely" be gay.

He was out with his bandmates Sally Salter and Patrice Okereke when the Nestene invasion of Earth began and only narrowly survived after the trio were cornered by several Autons before they were deactivated. After the ordeal, Mook started a romantic relationship with Patrice. (PROSE: Rose)

Behind the scenes
All three members of Bad Wolf (excluding Mickey) are exclusive to the novelisation and do not appear in the original television episode.