Snarler

Snarler is a level 39 rare black wolf that can be found patrolling north of the road in eastern Feralas. I have indicated where he can be found in red on the map below.

He drops the typical green item and a decent amount of experience for people leveling.

This particular wolf used to be highly sought after by hunters because he originally had an incredibly high amount of base magic resistance. That was fixed by Blizzard many moons ago however. He currently shares the same abilities as all of the other wolves in game but still makes a pretty nice looking pet. If your looking for this particular model and color and are having trouble finding him; there are level 16-17 elite wolves in Redridge Mountains, and level 32-33 wolves in the Hinterlands that look exactly like him.

Arash-ethis

Arash-ethis is a level 36 rare white wind serpent that can be found patrolling in one small area in north western Feralas, just south of Camp Ataya. I have indicated where he can be found in red on the map below.

He drops the typical green item and a decent amount of experience for people leveling.

He is also tamable by hunters and would make a nice pet for people who come across him. He shares the same model and color as a few other mobs in game, the most easily obtainable being the level 40 Cloud Serpents in Thousand Needles. He also has a twin rare spawn in Dustwallow Marsh called Hayoc.

Thartuk the Exile

Thartuk the Exile is a rare level 81 with approximately 74.3k health. He can be found wandering the road in northern Mount Hyjal starting at Nordrassil and continuing all the way past the Circle of Cinders. Do not be fooled by NPCScan overlay with this guy, it currently doesn't show the exact patrol area. He actually spawns much closer to Nordrassil than the overlay implies. I re-did the overlay patrol area in green on the map below to give you a better idea of where to look for him.

Thartuk the Exile drops Thartuk's Inimitable Gauntlets, which are bind on equip item level 325 physical dps leather gloves. He also drops around 20 gold, and for leveling characters killing him yields a hefty amount of experience. 

Uhk'loc

Uhk'loc is a level 53 rare white gorilla that can be found by Fungal Rock in Un'Goro Crater. Before Cataclysm he spawned inside the cave by the pool where the quest npc U'cha can currently be found. It is unconfirmed whether or not he still spawns there. I camped inside the cave waiting for him to spawn with no luck on and off for a couple of days. When I went outside the cave entrance to his new spawn location he showed up shortly after. I have marked both locations on the map below and I have included a screen shot of Uhk'loc in his new location further down this post.

He drops the typical green item and a decent amount of experience for people leveling.

He is tamable by hunters and would make for a very unique looking pet. He is one of only two white gorillas in the game, and both of them are rare spawns. The other is a level 28 non-aggressive rare named Tsul'Kalu, he can be found in Northern Stranglethorn. 

Crusty

It's Crusty the Crab! Crusty (who is clearly a Spongebob Squarpants reference) is a level 32 non-aggressive crab that spawns off the coast of northern Desolace. I have indicated his patrol area in red on the map below.

He drops the typical green item and a decent amount of experience for people leveling.

He is also one of only two rare crabs currently in game. The only other rare crab is Ghostcrawler, the level 85 spirit beast crab in Vashj'ir. If you are a hunter and are simply interested in taming a crab of this particular color, there are several others to choose from in game. They range from level 2 to 80 and can be found in Durotar, Wetlands, Tanaris, Howling Fjord and Kelp'thar Forest in Vashj'ir. This is also the same model and color that goblin hunters start out with.

King Mosh

King Mosh and the Savage Raptor Mount

King Mosh is a level 55 non-elite devilsaur. He used to be an elite level 60 mob with a whopping 61k health. Years ago he was a force to be reckoned with. During the Burning Crusade he would eat through level 70's with decent gear. Unfortunately his level has been reduced since Cataclysm, and he now has only 5,528hp.

King Mosh can be found in the north western part of Un'Goro Crater patrolling in a few different locations around The Screaming Reaches. I have indicated the locations where he can be found in red on the map below.

He drops the typical green item and a fairly high amount of experience for people leveling who come across him.

Time-Lost Proto-Drake - Reins of the Time-Lost Proto-Drake

The Time-Lost Proto-Drake (TLPD) is a level 80 rare spawn that can be found in the Storm Peaks. He has a 100% chance to drop the coveted Reins of the Time-Lost Proto-Drake, as well as a level 76 bind on equip necklace and an abandoned adventurer's satchel. He has 18,900 hp and is non-elite. TLPD shares a spawn timer, spawn points, and flight paths with Vyragosa. This means that they can never be up at the same time. Vyragosa is also MUCH much more likely to spawn than the TLPD. In your time camping for the TLPD you can expect to be seeing a lot of her.

Spawn Timer:

The spawn timer on both the TLPD and Vyragosa is somewhere between 6-24+hours, meaning that after either Vyragsa or the TLPD are killed you will not see either of them spawn again for at least six hours MUCH shorter than it used to be when this article was originally written. People have seen it in as little as an hour, and anywhere up to about 7 hours (updated 4/13/17). It is completely random which one of the two will spawn in next. Vyragosa could spawn 10 times before you see a TLPD spawn or she may only spawn a couple of times in between TLPD spawns.

TLPD being "held" at Bor's Breath, screen-shot courtesy of Reinoverall - Elune (US)

Spawn Points:

Putridus the Ancient

Putridus the Ancient is a level 80 elite rare flesh giant with approximately 75.6k health. He can be found patrolling a very large area between The Broken Front and Corp'rethar in Icecrown. I hiave highlighted his patrol area in red on the map below. He is one of three rare spawns in this zone. The others are Hildana Deathstealer and High Thane Jorfus.

Putridus the Ancient is part of the Northern Exposure and Frostbitten achievements. He drops Giant's Toewrap which are level 76 bind on equip leather bracers with a random enchant. Like other Northrend rares, he also drops Abandoned Adventurer's Satchel, which generally contains about 20 gold, a full stack of frostweave cloth, and often times a few crystallized elements. He's also worth a hefty amount of experience for people leveling in the area.