Corelings are mythical creatures found in the Demon Cycle series by Peter V. Brett. They are dark, malevolent beings that emerge at night, preying on humans. Corelings come in various forms, each with unique abilities and characteristics, such as the Ruin and Wight. These creatures are vulnerable to sunlight, which drives them away and weakens their powers. Humans in the series have developed various strategies and tools to defend themselves against corelings, including the use of warding symbols that can protect against their attacks.