You like him. He's cute, funny, and a demon in the sack. There's just one thing you don't have in common: Reading. And you'd really like to have that in common, because it's something you do all the time. Assuming he isn't like, "Books? You like those? Why?" (in which case DTMFA) here are some books to get him started.
The Action Movie Lover
Is he in line for every iteration of The Fast and the Furious? Is something always exploding or getting destroyed in every film he sees? Then for him, I recommend Sandman Slim by Richard Kadrey. This book plays like a Jason Statham movie in all the very best ways. Yeah, it's got some magic and stuff in there but mostly it's crazy violent and full to the brim with chasing bad guys. Did I mention the main character is a badass anti-hero? This book is a great intro to urban fantasy for your non-reading action movie lover.
The Military Buff
Does he have to watch Saving Private Ryan every time it's on? Is he interested in guns and ammo and tanks and fighter jets? Does he play "Call of Duty" or "Gears of War" or "Starcraft" with his bros like it's his second job? Then I'd give some military science fiction a shot for him. If he's more of an alien blaster, give him The Lost Fleet by Jack Campbell. It has spaceships and lots of kaboom and a tortured hero. If he's less aliens and more war-on-Earth, give him Terms of Enlistment by Marko Kloos. It's near-future military science fiction that follows a new kid through becoming a soldier and into the hell that is war.
The British Humor Enthusiast
Does he regularly subject you to British humo(u)r? Does he quote Monty Python until you're ready to choke him if he makes another "Knights who say Ni" joke? Usually, this kind of guy already reads, but on the off chance he doesn't - and I have met them - there is a book that was basically created just for him. Pick up Good Omens by Terry Pratchett and Neil Gaiman. It's all the British humour you could want, plus the impending apocalypse. You can't go wrong with that.
The Too Smart for Fiction Guy
You know that guy who's super educated and really smart and likes math and learning things but somehow hasn't ever really read much fiction? Creativity isn't his thing. In fact, spending time on stuff like that is kind of juvenile, as far as he is concerned. I live with this stereotype and after some trial and error, I struck gold with A Game of Thrones by George R. R. Martin. He was completely enthralled and tore through the whole series. It's got magic and stuff in there, sure, but it's largely a political thriller.
The Spy Movie Aficionado
Does he love James Bond? Is Jason Bourne on his Christmas card list? Did he make you sit through not just Taken (which was fine) but also Taken 2 (you must really like him)? For the man who likes tough-but-smart guys solving complicated mysteries, I'd go with Altered Carbon by Richard K. Morgan. It's dark and violent and features exotic locales. It's more Casino Royale than The Man with the Golden Gun, though, so if he likes nu-Bond, this is for him.
Classic science fiction can be tough going. Things like Snow Crash or Stranger in a Strange Land explore cool concepts in strange, innovative ways and you might love them but they are tough going for someone who isn't used to reading let alone reading Big Idea science fiction. Bring them in with something entertaining, fun, and cool of the type they already like in other media. Think less "high end sci-fi" and more "gateway drug." Once they're hooked, you can gradually bring them along to the harder stuff. Thus do we (hopefully) create another addict.
(Thanks to all my Twitter folks for a great conversation on this and some great recs from @kindleaholic, @TommySalami, @DjHellYeah, @MattMc1 @UkeleleDan, @Geese_Juggler, @SpaceCoastLaw, and @ShariSlade)