Viper

Vipers are a new strain of zerg fliers being incorporated in the upcoming expansion StarCraft II: Heart of the Swarm. They have the ability to pull allied units to safety or enemy units to their doom, but also the capacity to create a cloud at a location, hindering ranged enemy units' attacks and skills (due to this, it is likely that the viper is an evolution of the defiler).

Additional information

 * Revealed at BlizzCon 2011.
 * The trailer contains a clip that shows two vipers using their long tongues to pull two colossi into a lot of zerglings.