Starks Parker books are awesome, no supernatural, a vit colder than Jack, but just as ruthlessly efficient. Parker is a professional thief who always gets the job done, messily sometimes, but done. 20 something books in the series, unfortunately, Stark(Donald Westlake) passed away a few years ago.
MacDonalds Travis McGee books are also a great read, McGee is kind of a mercenary for hire, doesn't like to kill, more of a lover than a fighter really, but you don't want to be on hi shit list. No supernatural again, but again like Jack brutal efficiency. 21 books I think and again MacDonald died years ago.
I'd also 3rd the Dresden series, Harry is pretty much a badass and I haven't disliked one of the books yet.
The list of this genre goes way back, the times have of course varied the interpretations, but the field is rich with good characters