Sun Bat
The Sun Bat is a Hardmode enemy found in the Underground and Cavern layers. It flies around with the typical bat AI, but it inflicts both the Holy Flames and On Fire! debuffs on contact, making it dangerous to get hit by. It always emits a bright yellow glow, however, making it easy to spot.
It can drop Essence of Sunlight when killed, being one of the few non-Space enemies to do so.