Goblins breed with notorious speed, and their industriousness in this occupation, aside from providing numerous warriors to replenish the ranks, results in a rather high frequency of physical mutations. Aside from the usual bugbear and hobgoblin, there are a variety of other goblin mutations:

Caveling (CR +0): These goblins hail from the deeper parts of the world. They gain darkvision 60 feet, light blindness, two claw attacks that deal 1d3 damage, and a climb speed of 20 feet.

Gibberling (CR +1): These goblins have been touched by aberrant influence. They gain light sensitivity and the gibbering ability (see gibbering mouther) which can be activated as a move action with a range of 30 feet.

Hellion (CR +1): These goblins are born of dark energies, and are immediately identifiable by the flames that dance in their mouths. They are immune to fire and gain a bite attack that deals 1d4 damage plus 1d6 fire damage.

Lasher (CR +1): This type of goblin has an unusually long tongue. As a standard action, they can use their tongues to perform disarm or trip attempts against targets within 10 feet with a +2 racial bonus and without provoking attacks of opportunity.

Thorn (CR +1): Some goblins are born covered in soft thorns that grow rigid as they mature. These goblins gain a slam attack that deals 1d3 damage plus grab. In addition, a creature in a grapple with the thorn takes 1d3 damage at the beginning of the thorn's turn, and any an attacker who successfully strikes the thorn with an unarmed attack or natural weapon take 1d3 damage.