Raven

The Raven, formerly known as the Nighthawk, Vulkan and the TF-620 Nomad,  is a terran air unit to be featured in StarCraft II. It is based on constructing objects and is operationally linked to an AI.

Game Unit
The Raven is analogous to the science vessel of the original StarCraft, and are "primarily support craft" for the terran factions. They have no standard attack of their own. They are strong against s and high templar.

Wings of Liberty
In StarCraft II: Wings of Liberty, Ravens are unlocked through research. This costs 20 protoss research points.