- Dark Whelpling
- Binds when used
- Item Level 30
- Use: Right Click to summon and dismiss your whelpling.
A Dark Whelpling pet
The Dark Whelpling item summons and dismisses a Dark Whelping, a dragon whelpling small pet that follows you around, meaning it is a non-combat pet and will not aid you in battle.
Source
Dark Whelpling drops from Scalding Whelps in the Badlands and from Searing Whelps in Dustwallow Marsh. The Badlands is the place of choice as the Dustwallow Marsh whelps are mixed in with a lot of other mobs that don't drop the pet. On the flip side, you will probably dealing with more competition at the Badlands on more populated servers.
Notes
The drop rate of this pet is roughly 0.01% (one in every thousand kills) and takes an incredible amount of patience and determination in order to get one. Due to the difficulty of obtaining one, and thus their rarity, they can sell for fairly large amounts of gold on the Auction House, at least as far as pets are concerned.
Unlike the other two Whelpling pets, the Dark Whelpling is one of the pets which plays a sound when you target it.
See also: 
[Tiny Crimson Whelpling], Tiny Emerald Whelpling