The Byakhee often serve Hastur the Unspeakable. Since the beings are made of ordinary matter, they can be injured by normal weapons such as firearms. Byakhee can fly through space and can carry a rider, though the rider needs protection from the vacuum and cold by suitable spells or potions. One hypothetical form of protection from interstellar space is an elixir known as space mead, whose side effects are unknown. Byakhee live in interstellar space but may be summoned to Earth to perform tasks or to serve as steeds.