Scary snake

RATTLER

Its warning sound gives away its name before you even see it slither by.

"Scary snake" points to "rattler" because it’s a common nickname for a rattlesnake, a venomous snake known for its intimidating rattle sound. The word itself also carries a slightly ominous tone, making it a natural fit for something frightening. No hidden wordplay here—just a straightforward clue matching a well-known reptile.