Wyvern

Wyvern is a long, white dragon-like creature, which appears to spawn in Floating Islands but also seems to spawn anywhere if a player is high enough, even directly above the start point of a map.

The Wyvern attacks like a Devourer or Bone Serpent, making long, sweeping passes. Fighting them at high altitude and taking advantage of the lower gravity is useful for dodging, since they can do a lot of damage quite quickly. Weapons or Spells that strike a target multiple times (ex; Demon Scythe) are your best bet for fighting the Wyverns, as with any other worm.

Wyvern is shown in a dev blog post, where appeared as non-hostile creature, and in the 1.1 trailer.