The Prince by Niccolo Machiavelli
The Prince is traditionally treated as though it were a beginner's guide to being a complete and utter bastard, which is strange, because it doesn't seem to even be vaguely worthy of this title. Maybe years of Risk and Civ have made me blind to the underhandedness of Machiavelli's tactics, but I struggled to see the controversy inherent in his theories of renaissance Italian politics. If anything, The Prince suggests that a leader should be a man of the people, surrounding himself with differing opinions and participating in everyday society within his city, rather than the kind of two-faced archvillainry that the term 'Machiavellian' has come to denote.
Titus Groan by Mervyn Peake
A masterpiece of pre-LOTR fantasy literature, Titus Groan is a grotesque gothic novel concerning Gormenghast, a castle steeped in ludicrous tradition and comic weirdness, and the disruption to it's ritualistic day-to-day happenings that occurs when a new heir (the titular Titus Groan) is born to the manor, and as a servant boy called Steerpike manipulates his way into a trajectory of upwards social mobility through Machiavellian and underhanded means. One of those books where you can get lost in the genius and the flow of the language alone, let alone the compellingly bizarre and eccentric characters.
And Another Thing by Eoin Colfer
It's almost Douglas Adams, but not quite. This official sequel to the Hitchhiker's Guide To The Galaxy books, the first written since Adams' death, evokes a similar style to the late, great author's own work, especially the style found in the later books So Long and Thanks For All The Fish and Mostly Harmless with a little bit of influence from the Dirk Gently novels, but never quite reaches the heights of the original three Hitchhiker's guide novels. Still, it's a more than competent romp through an increasingly silly universe, has plenty of callbacks to characters and ideas from the earlier novels, and it wraps up that whole 'everybody dies' ending from Mostly Harmless in a much less depressing manner.