Gestapo Mars by Victor Gischler

Carter Sloan is a trained assassin—the best there is, pulled out of cryogenic sleep whenever an assignment demands his skills. So when he's kept in the deep freeze for 258 years, he's seriously pissed off.
Yet his government needs him, to hunt down the enemy known as the Daughter of the Brass Dragon. The future of the galaxy-spanning Reich depends on it, so Sloan is off—screwing, swearing, and shooting his way across interstellar space.
lt's action, adventure, and disgusting gelatinous aliens as only Victor Gischler can create them.