The Jockey

The Jockey is a new form of Special Infected that appears in Left 4 Dead 2. Jockeys jump onto the Survivors and cling to their head and upper-back. From there, they can steer the Survivor while clawing them. The Infection has caused the Jockey to mutate a large amount of muscle upon his upper back and neck, causing him to hop around in a spider monkey motion. His fingers and toes have also increased in length, adding to his baboon-like profile. His lips and the skin surrounding them have also deteriorated away, giving him a more skeletal look at the mouth area. He has pupils, like the Spitter. He wears a tattered white t-shirt and blue boxers. He has a gibbering, ape-like vocalization, and cackles hysterically whilst attached to a Survivor, according to Valve commentary, the mutations have caused Mania in the Jockey, causing the Jockey to laugh incontrollably.

The Jockey is a Special Infected that has animal-like characteristics. The Jockey can use his ropey frame to jump long distances at a time, though not as far as the Hunter can, nor without the need to crouch to charge up the ability. When on a Survivor, he claws at them with his free-hand while leaning in a direction to cause the Survivors to stumble. Again, the clawing does not do as much damage as the Hunter does (dealing only 1 damage at the Easy and Normal difficulties). The player can try to steer in a better direction, but can't outright resist where the Jockey drives them. When a player is incapacitated, the Jockey leaps off of the Survivor. When a Jockey successfully incapacitates someone and jumps off, it will take approximately 30 seconds before it can jump onto another survivor. However, if the Jockey was knocked off the recharge-rate will be considerably shorter. [citation needed]

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.

Gameplay
When playing as the Jockey, his hands are like the Hunter's, except they are curved downward, and the arms are sticking out straighter. The hands are always twitching and shaking, and he is almost always laughing. While there is a Jockey on the back of a Survivor, the Survivor can still move to resist the Jockey's influence over them, though this only has a slight resistance and will merely slow the Survivor to a walk.

Survivors

 * When someone is grabbed by a Jockey, one way to help them is to melee them, then shoot, although this is contrary to the advice of shooting then shoving immediately after. When using your melee attack to free a caught Survivor, remember than you need to melee the the Jockey himself, not the Survivor.
 * If attacked by the Jockey, try to push to a table or a dumpster to delay the movement.

Infected

 * Jockeys are very useful when facing a lone wolf Survivor as they can lead the victim further astray: simply jump on them and pull them from their team until they're downed.
 * However, Jockeys can adapt to almost any situation: pulling a Survivor away from the team into any kind of danger can easily turn the tables.
 * Hide behind your victim (via mouse-movement) so there's a better chance they shoot your victim and not you.
 * The Jockey's main job is to steer the survivors apart. Try to pull a Survivor somewhere that will cause trouble for his/her friends; for example: towards a Hunter/Boomer/Smoker/Charger, into a Witch's personal bubble, or into Spitter goo.
 * NOTE: A Jockey controlled survivor will move slower if the survivor is in limp-rage (i.e. below 40 health).
 * Just like a Hunter, the Jockey can push Survivors away from the one attacked so use it to your advantage when possible such as a Boomer attack to stun the masses.
 * When you are a Jockey, try to run your victim into dangerous obstacles, such as Spitter-acid, Boomers, hordes of common-infected, off of ledges, into Witches (they don't like people in their comfort-zone) and fire. If there are none of these nearby, just separate the Survivor from the group. In this game's Versus mode, compared to Left 4 Dead, health bonuses are gone; it's all about if the Survivors finish the level.
 * Jockeys can work in combo with the Spitter and the Hunter. Use the Jockey to separate the survivors, have a nearby hunter pounce the survivor, making the Jockey jump off (less recharge time than if you down them), and have a Spitter spit on the hunter dealing colossal damage. Also if there is nobody else around steer a Survivor away and have a Charger charge a Survivor in an out of the way place. Chargers can do massive amounts of damage in seconds!
 * Use ledges to put Survivors in a hanging stance as this will cause a distraction for the remaining Survivors while you move in for the second Survivor.

Behind the Scenes
Originally, the Jockey was said to have a very colorful shirt. This was later changed to his current look at an unknown point.

Trivia

 * This is the first Infected which can leap off the Survivors, not having to kill them. He can also hop off after incapacitating a Survivor.
 * As seen in Gameplay Videos, the player can resist the Jockey by walking in the opposite direction. When resisted, the Jockey becomes slower for a few seconds, allowing fellow teammates to reach the player.
 * Gameplay footage of the Jockey shows that his "pounces" for his primary attack are much shorter and quicker than that of the Hunters', supporting the theory that all the new Special Infected have less advanced cases of infection. This also means players will have to have good accuracy when attacking, or focus on Survivors distracted by other Infected.
 * The Jockey is currently the Special Infected with the smallest profile.
 * The Jockey and the Tank are the only two playable Special Infected without the suffix "-er" in their name and both do not take addition damage from headshots.
 * The Jockey bears more than a passing resemblance to the "Fleaman" enemy from the Castlevania series. Both have a small stature, both leap about like monkeys, and both can latch onto and control something (Survivors in Left 4 Dead 2, giant, skeletal serpents in the Castlevania series).
 * The Jockey may be a reference to one of the "Mutants" in the Movie "Wrong Turn," as one of them is constantly cackling and also has a hunchback.
 * The Jockey's cries during the period that it performs its special attack sounds similar to that of a ravenous chimpanzee or baboon.
 * When being ridden by a Jockey, the survivor is surrounded by a green light, unlike the red light when being pounced by a Hunter, choked by a Smoker or pummeled by a Charger. That's may be by the fact he's the only Special Infected that you can do something while being attacked (resist).
 * A Jockey's pounce can be stopped by a well placed melee attack, just like a Hunter's can.
 * The achievement "Rode hard, put away wet" shares a name with a Sniper's "Jarate" achievement in Team Fortress 2.
 * Oddly enough, when you look at a Jockey from a different person's perspective, he looks as if he is very close to the ground, and his head is almost touching it. But from a Jockey's view, he looks as if he is standing upright like any other infected.
 * The Jockey does not stop laughing until it is dead.
 * Some gamers refer to the Jockey as a "head humper". This is a reference to the Headcrabs from Half Life 2.