"Agent of Change" by Miller & Lee is about an Assassin and a Mercenary soldier that meet cute.
"A Desert Called Peace" by Tom Kratman about a retired professional soldier that starts a world war to revenge his family that was killed in a 9/11 type terrorist attack.
"Monster Hunter International" by Larry Correia is about an accountant attacked by a werewolf that survives the attack by throwing him out the window of a skyscraper. Then he gets violent.
They have a bunch of Drake's Hammer's Slammers series and most of Weber's Honor Harrington series and a ton more cool stuff.
I've always been partial to Gordon R. Dickson. Anything in his Dorsai series (actually the "Childe Cycle, officially) is good.
But two of his little know early novels are also great. Check out "Wolfling" and "The Hour of the Horde". You can find the paperbacks on Amazon.
Marrion Zimmer Bradley had a good tough-guy main character in "Hunters of the Red Moon".
John