Walkers appear the same as normal zombies you would expect from similar zombie shows. They have blood stained clothing, nasty teeth, sharp claws, and they appear to have blank, soulless eyes.
Walkers are normally slow, and they have low health and are very predictable. Walkers are the easiest zombies to defeat in the series.
Depending on how the Walker attacks, it may deal so much damage that it actually kills the victim in one scratch...or bite.