Wolf

Wolves are neutral mobs that were added in Update 0.9.0. The player can tame them by feeding them Bones. They were the first tameable mob in the game.

Wild
Wild wolves spawn in Taiga, Plains, and Forest biomes. They wander aimlessly, but will sometimes coordinate and kill Sheep, Skeletons, and Rabbits. When doing so, they will gain the appearance of aggressive Wolves.

Aggressive
Wild Wolves (see above) may turn hostile towards the player if they, or nearby Wolves, are attacked. Aggressive Wolves have red eyes and black patches on their fur. Their tail is also raised higher than wild Wolves.

Tamed
Tamed wolves follow the player around the world, and teleport towards the player if they are too far. They shake themselves dry after exiting any body of Water, and can be made to sit and stand by pressing the 'sit' or the 'stand' button respectively.

Wolves can be healed by tapping and holding them with any type of meat or any type of Fish. Their collars can be dyed by pressing them with any Dye, but by default, the collar is red.

Tamed Wolves will chase and kill Skeletons without provocation.

Breeding
Tamed Wolves can be bred using any type of meat if their health is fully restored, including Rotten Flesh, which will not poison them. When bred, a puppy spawns, which is already tamed.

Wolves cannot be bred until they are tamed.

Combat
Tamed Wolves attack any mob the player attacks or attacks the player, and will attempt to kill it. Wolves can easily kill Skeletons, Zombies and Spiders, but face trouble against Creepers and Endermen, the former due to their explosive power and the latter due to their high health and teleporting ability.

Trivia

 * In early Update 0.9.0 beta builds, tamed Wolves had a black collar.
 * Tamed Wolves can enter love mode while sitting.
 * However, they cannot breed until they are made to stand.
 * Also, Wild Wolves can be fed but they can't breed.
 * Bug: Before Update 0.10.0, Baby Wolves couldn't swim in deep water and would drown.