"Jesus," she said. "It must be hard being you."
Hawk was quiet for a time, then he smiled at her, which was nearly always a startling sight.
"Worth it, though," he said. - Cold Service
Hawk is Spenser's primary ally and best friend through most of the books. Hawk first appears in the third Spenser book, Promised Land, as an enforcer sent to threaten Spenser's client. Spenser and Hawk have known each other since their late teens, when both were on the same boxing circuit.
Hawk is very much like Spenser, a little taller than 6'1" and extremely fit. He is considered a very dangerous man, who works as a bodyguard, enforcer, and hit man. Hawk is always very stylishly dressed and drives expensive cars; his preferred drink is top-quality champagne. He has spent time in the Foreign Legion and in Cuba and Indochina. He occasionally travels out of town for a job, once earning $200,000 for a week's work in Miami. (Spenser says he did not ask Hawk what he did for the $200,000.) Within the series, Hawk kills a number of people, although often with less provocation than Spenser. (For a partial list of people Hawk kills, see Homicides.)
Although he has fewer scruples than Spenser, Hawk is otherwise very much like him - self-contained, remarkably literate, and a man of his word. Hawk's accent varies widely, ranging from a deep ghetto accent to pitch-perfect upper-class WASP, depending on how he's feeling.
Hawk knows Boston's underground even better than Spenser and is widely known, and sometimes admired, by crooks on the street. He has many lady friends (women are frequently seen to hit on him in various books) but few serious relationships. He cares for Susan Silverman nearly as much as Spenser. His most serious relationship is with a thoracic surgeon, Cecile, who eventually leaves Hawk when she realizes he can't open up to her as much as she'd like.