I've been hooked. What can I do?

Normally, you will die. Except if...

Factors outside of your control:

• Roadhog's competence. One that is completely new at the game might not shoot you in time, giving you enough leeway to use a defensive ability.
• Roadhog's lag.
• An ally saved you: you have an armor pack, zarya bubble, a mei wall, another hook, etc disrupting the roadhog combo.

Factor partially in your control:

• There is a bug with fast moving characters that will sometimes have you hooked behind or to the side of the Roadhog. If you are genji, tracer, or lucio, this seems to happen more often if you are moving around very quickly.

There is no skill that makes you escape from a Roadhog hook. He can shoot mid-hook, and therefore will hit you with his shotgun while you are still stunned. Some Roadhogs don't utilize this, and one tip is to hold the "escape" (Mei Cryo-Freeze, Tracer's Recall, etc.) button down, instead of smashing it 10 times a second. Like this, the skill will activate as soon as it can be activated.

You can deal with Roadhog by staying at long range. Due to his big model, he is easy to hit, even at long range. If you can't stay at long range, stay behind your tanks. If you play a fast character like Tracer, you can kite him around or bait out the hook.

tl;dr: Avoid getting hooked. Once Roadhog hits you, you're dead.

As Tracer, Genji, and other heroes with dashes, you can dash as soon as the pull duration is over, and jump to safety out of range of Roadhog's devastating gun. The heroes I have done this with are Tracer, Genji, Mcree, and Widowmaker.

Alternatively using Mei's ability where she turns to ice, or Reaper's ability to phase out, you can avoid getting hit by a shotgun blast if you react fast enough. Although this only really delays the inevitable as Mei, unless you team can get there fast enough.

Zarya is also a good pick, as you can shield yourself after you get hooked, and absorb the damage from Roadhog's gun. The main thing to succeed in countering him with any of these abilities is having quick reactions so you can use the ability before he shoots you and you die.

Note: None of these guarantee that you will live, however if the Roadhog miss-times his combo, you will have a better chance of surviving if you attempt to dash/shield/go untargetable as soon as the hooks disable wears off.