"Starwolf" is actually a collection of three novels from the late 1960s: "The Weapon from Beyond," "The Closed Worlds," and "World of the Starwolves".
The Starwolves are Viking-like space pirates whose world's harsh gravity imparts to them a superhuman strength and musculature. Morgan Chane was almost one of them...though his family had come from earth. Finding himself an outcast after killing a fellow Starwolf in a feud over their plunder, Chane joins a band of tough interstellar mercenaries to survive. However, his troubles are not over--if any but Dilullo, the aging Merc in charge of the mercenary band, learns his secret, his life could be forfeit, for Starwolves are considered such a menace that they are usually shot on sight.
These books owe a lot to "Conan: The Barbarian," some to the pulp SF books of the 30s and 40s, and a bit to "The Stainless Steel Rat". Though somewhat derivative, they are nonetheless competantly and entertainingly written, with sufficiently interesting characterization, that they are well worth the time they take to read.