Eco-terror films, also called "nature-run-amok" or "natural horror" films or "eco-horror" films, focus on an animal or group of animals that are far larger and more aggressive than is usual for its species, terrorizing humans within a particular locale whilst a group of other humans attempt to hunt it down. This genre began in the 1950s, when concern over atom testing led to the popularity of movies about giant monsters. These were typically either giant prehistoric creatures awakened by atomic blasts, or ordinary animals mutated by radiation. These films included Godzilla, Them!, and Tarantula. The trend was revived in the 1970s as awareness of pollution increased, with corporate greed and military irresponsibility being blamed for destruction of the environment. Night of the Lepus, Frogs, and Godzilla vs. the Smog Monster are examples of these movies. After the massive success of Steven Spielberg's 1975 Jaws, a number of highly similar films (sometimes regarded as outright rip-offs) were produced in hopes of cashing in on its success. These included Alligator, Cujo, Day of the Animals, Great White, Grizzly, Humanoids from the Deep, Monster Shark, Orca, The Pack, Piranha, Prophecy, Razorback, Blood Feast (Night of 1,000 Cats), Tentacles, and Tintorera. Roger Corman was a major producer of these films in both decades. The genre has experienced a revival in recent years, with films such as Mulberry Street and Larry Fessenden's The Last Winter reflecting concerns over global warming and overpopulation.
The Sci-fi (now known as SyFy) Channel is a massive producer of such films with their original movies often consisting of nothing more than, "Giant _____ attacks!" Examples include Sharktopus and Dinoshark.