Fish, Crustaceans, and Molluscs
- Attack of the Crab Monsters (1957; abnormally large crabs)
- The Beast (1996; aggressive giant squid)
- Deep Rising (1998; giant deep sea squid-like creature)
- Deep Shock (2003; giant intelligent electric eels)
- DeepStar Six (1989; reptilian crustacean)
- Frankenfish (2004; mutant snakehead)
- It Came from Beneath the Sea (1955; giant octopus)
- Kraken: Tentacles of the Deep (2006; giant squid)
- Leviathan (1989; various sea creatures)
- The Monster That Challenged the World
- Octopus (2000; giant mutated octopus)
- Octopus 2: River of Fear (2001; giant mutated octopus)
- Piranha (1978; genetically enhanced piranhas)
- Piranha II: The Spawning (1981; genetically altered piranhas)
- Piranha (1995; mutant piranhas, remake of 1978 same name film)
- Piranha 3D (2010; prehistoric piranhas, remake of 1978 same name film)
- Piranha 3DD (2012; sequel to Piranha 3D)
- Mega Piranha (2010; megapiranha)
- The Sea Beast
- Snakehead Terror
- Tentacles (1977; abnormally large octopus)
Read more about this topic: List Of Natural Horror Films