From Sonic Retro
Dark Fright is an Dark Gaia minion encountered by Sonic the Werehog in the night stages of Sonic Unleashed. They are small, balloon-like enemies which hover about a foot above the floor. Dark Frights frequently attack in packs, appearing en masse in puffs of supernatural smoke, and Sonic is often required to destroy all the Frights in one area in order to progress through the level.
Dark Frights lack any sort of projectile attack, and instead damage the Werehog by cannoning into him at high speed. Their quick dashing means that it can be difficult to catch them when trying to eliminate a whole herd. Like the Rex, Sonic can pick up Dark Frights and throw them at other enemies, although they don't do as much damage.