The eastern copperhead (Agkistrodon contortrix) also known as the copperhead is a species of venomous snake, a pit viper, endemic to Eastern North America; it is a member of the subfamily Crotalinae in the family Viperidae. Its generic name is derived from the Greek words ancistro (hooked) and odon (tooth), or fishhook. The trivial name, or specific epithet, comes from the Latin contortus (twisted, intricate, complex); which is usually interpreted to reference the distorted pattern of darker bands across the snake's back, which are broad at the lateral base but "pinched" into narrow hourglass shapes in the middle at the vertebral area. Five subspecies have been recognized in the past, but recent genetic analysis shows that A c. contorix and two of the subspecies are monotypic, while Agkistrodon laticinctus (formerly Agkistrodon contortrix laticinctus) and the fifth subspecies are a single distinct species (see subspecies table below).
It is a common species in many areas within its range, which may lead to accidental encounters with humans.