Name: Colin Sullivan
First Appearance: The Departed (2006)
Number of Appearances: 1
Enemy of: Billy Costigan
Note: infiltrates police on behalf of the mob
The character "Colin Sullivan" is based directly on the character "Lau Kin Ming" in the "Infernal Affairs" film trilogy.
Colin grew up in the Southie Projects. As a child, he was very religious, an exception student, and a good person. But when he was 12 years old, he met Irish mob boss Frank Costello, who became his father figure and changed the course of his life.
Suggested links for further research about this character and the character's religious affiliation: