The Jockey

The Jockey is a new form of Special Infected that will appear in Left 4 Dead 2. It will attack Survivors from behind and jump onto and cling to their head and upper back. From there, they can control the Survivor while doing so. It appears that the Jockey has been mutated by the infection to the extent that he has a hump, which is what causes him to hop around in a spider monkey like motion. However, he can jump great distances, yet nowhere near as far as the Hunter. His lips and the skin surrounding have also deteriorated away. When on a Survivor he claws at them with his free hand while leaning in a direction to cause the Survivors to stumble. The player can try to steer in a better direction, but can't outright resist where the Jockey drives them. He has large claws, used to help control the Survivors, and wears a loose vest alongside blue boxers. His approach can be denoted by his loud, maniacal cackling. Like the Spitter, it too appears to have pupils. It was first mentioned here.

In this article, Valve said that the Jockey was made to work in tandem with the Spitter by "steering" survivors into the Spitter's goo. Valve also said that the Jockey could steer survivors into fire or even witches.

One could argue that the Jockey is superior to the Hunter in pouncing isolated survivors as it can also "steer" them away from the rest of the team at nearly the speed of the survivors.

Trivia

 * The Jockey has some resemblance to Igor from "Frankenstein".