Deer

Deer are level 3-5 critters found in many forested parts of the world, such as Elwynn Forest, Teldrassil, and the Moonglade.

Deer are skinnable although typically only drop Ruined Leather Scraps with the occasional piece of Light Leather. Still, they can be an easy source of leather for very low level characters - although as a critter they do not reward xp, so perhaps your lowbie is better served hunting beasts!

There are wide variety of deer, some of which have horns year round. Deer are typically medium sized animals and faster than elk. Some varieties, such as impala, live in tropical regions. Mountain deer may have the ability to spring, effectively traversing rocky terrain at three/fourths their normal speed. From mountain deer to mighty northern alpine moose, they are the primary prey of wolves and other predators. Humans typically hunt the smaller deer, while orcs prefer the challenge of an elk or moose.

Other deer

 * Infected Deer are found in the Western Plaguelands.
 * Sickly Deer are found in Darkshore.
 * Fawn are found in Elwynn Forest.
 * Cured Deer are found in Darkshore.

To All The Squirrels I've Loved Before
For those attempting to complete the achievement there are also a few Deer in Chillwind Point (up near the road on the West side of the river; approaching Chillwind Camp). This location can be handier for Horde characters. Otherwise Deer can easily be found in Elwynn Forest, Teldrassil, and the Moonglade as noted above. "Other Deer" do not count towards the To All The Squirrels I've Loved Before achievement.