Selena Gomez
From Tardis Wiki, the free Doctor Who reference
Selena Gomez was an employee or affiliate of Torchwood One who Yvonne Hartman insisted could handle the Xylophron Plasma while Yvonne had her night off. According to Tommy Pierce there was some doubt in this matter. The plasma soon threatened the entirety of London. This was apparently Selena's fault, as Yvonne later rued that she couldn't have one bloody night off. (AUDIO: Dinner for Yvonne)
Behind the Scenes
Selena Gomez is, in real life, a famous singer and actress. This is never mentioned throughout the entirety of Dinner for Yvonne. Selena Gomez is likely not a professional spy in real life.