Who said "Death is the only certainty in life, and I should know."?

This quote is attributed to Grim.

Death is the only certainty in life, and I should know. - Grim

"Death is the only certainty in life, and I should know."

Grim Death

"I'm a creature of pure evil, and I find your optimism... disturbing."

"Foolish boy, your mortal comprehension cannot fathom my dark intentions."

"Death is my business, and business is good."

"Your pitiful existence amuses me."

"Death doesn't scare me anymore."

"Death and I are old friends."

"Welcome to my world."

"Death is just the beginning."