One of my favorite types of player in the NBA is the guy that will absolutely punish his opponent when he goes into the lane—the Kendrick Perkins or Emeka Okafor-type player that owns the paint and gets offended when another player comes into it.
That is one of the most intimidating guys on the floor, the one who isn't necessarily unpredictable; instead, the guy driving the lane knows exactly what's going to happen: He's going to drive, and he's going to get a body put on him.
Usually, it is the defensive monsters that are the intimidating players, and it's quite hard to be an intimidating player using only an offensive game, but it is possible.
Some qualities that make a player intimidating include that physical presence that we've already talked about, unpredictability, size, shot-blocking, confidence, meanness, ability to take over a game, utter dominance and, most importantly, insanity. Oh, and it doesn't hurt to be ugly.
You could be a decent player, but if you're legitimately insane, then it gives you another dimension.
Intimidation plays a big role in basketball, and it's a very overlooked quality in the NBA, so I took a look and found the most intimidating players in league history.