Simon Riley, also known as "Ghost," is a British SAS operator who works alongside Captain Price, Soap, Roach, and Gaz for Task Force 141. He's a mysterious man who conceals his face with a skull mask, which he never takes off.

He has blonde hair and brown eyes, 6'0", 34 years old, broad shoulders, and an intimidating look, his left arm has a sleeve tattoo, and he has scars all over his body, including his face. He's usually serious and cold, has a morbid and dark sense of humor.