Films: Proteus (1995)
Location: Haunted home
Height/Weight: Grows to that of a small building.
Summary: Science goes too far. Again. And this time, the most dangerous predator in the seas is about to get a meaner streak than ever. It all starts with some mutations, an ego, and drugs.
History: Away from society is a Brinkstone Corporation rig. It has long since been abandoned ever since the Proteus project went out of control. The idea, if you can call it that and not a complete lapse in logic, was to mutate a great white, named Charlie, and make it more advanced. They succeeded. The shark grew smarter, but at the same time developed an uncanny power to shapeshift after absorbing people. Then it absorbed a heroin addict, and now it can't get enough of it. Time for the visiting folks to put this monstrosity out of its misery.
Notable Kills: Everyone it absorbs isn't quite dead. You can still hear the screams...
Final Fate: After mutating into a grotesque abomination of a shark/octopus/thing, Charlie is dowsed in kerosene, set on fire, and blown up. However, it seems to have corrupted the helicopter pilot that arrives in the end...
Powers/Abilities: Charlie can absorb people and take their intelligence and genetic code, giving him the ability to shapeshift.
Weakness: A crippling addiction to heroin can throw Charlie off at inconvenient times. Also, anything conventional.
Scariness Factor: 4.5-Charlie sounds like the most insane idea on paper. A mutant shapeshifting giant shark with a heroin addiction. Well, now it's here, and it'll take you into its conscious so that you can feel its pain forever. Aside from the horror of being perpetually part of this thing, there's also how horrifically malformed it actually is.
Trivia: -The novel this film was based on was known as "Slimer". Its plot was mostly the same, except a lot more characters were jerks, and Charlie was given a compound known as "Phoenix", triggering his mutation.
-Almost everyone had to wear thick rubber socks during the action sequences due to all the water. At least one guy got fed up with getting his feet all blistered, even though there was always a chance everyone would get electrocuted otherwise.