Nigel is the agent for the group The Be Sharps.
He discovered the group while they were performing at Moe's Cavern, where he became their agent. Nigel supposedly has a tattoo under his hair. He is very cruel and tries to get away with many things. He usually poses as an agent but then ends up tricking his clients. He consistently tried to trick his clients and take advantage of their success. 
Non Canon Appearance
Nigel can also be seen in some of the Simpsons Comics. In one comic, Nigel becomes the agent of Santa's Little Helper after he becomes famous. Once again he attempted to make a profit off of his client's success, even going so far as to thwart Bart's efforts to win his dog back.
Already mentioned on his bios==
- Episode – "Homer's Barbershop Quartet" (flashback)
- Comic story – Hamburger's Little Helper
- Comic story – Faking the Band