Grizzly (also known as Killer Grizzly on U.S. television) is a 1976 American horror thriller film directed by William Girdler, about a park ranger's attempts to halt the wild rampage of an 18 ft tall, 2,000 lb man-eating grizzly bear that terrorizes a National Forest, having developed a taste for human flesh. However, a drunken hunting party complicates matters. It stars Christopher George, Andrew Prine and Richard Jaeckel. Widely considered a Jaws rip-off, Grizzly used many of the same plot devices as its shark predecessor, which had been a huge box office success during the previous year. The giant grizzly bear in the film was portrayed by a Kodiak bear named Teddy, who was 11 ft tall.
The film opens with military veteran helicopter pilot and guide Don Stober (Prine) flying individuals above the trees of a vast national park. He states that the woods are untouched and remain much as they did during the time when Native Americans lived there.
Two female hikers are breaking camp when they are suddenly attacked and killed by an unseen animal. The national park's Chief Ranger, Michael Kelly (George), and photographer Allison Corwin (Joan McCall), daughter of the park's restaurant owner, decide to follow a ranger to the primitive campsite to check on the female hikers. There, they discover the mangled corpses of the two girls, one of which has been partially buried.
At the hospital, a doctor tells Kelly that the girls were killed by a bear. The park supervisor, Charley Kittridge (Joe Dorsey), blames Kelly for the attacks, saying that the bears were supposed to have been moved from the park by Kelly and naturalist Arthur Scott (Jaeckel) before the tourist season began. Kelly and Kittridge argue over closing the park before deciding to move all hikers off the park's mountain, while allowing campers to remain in the lowlands. Kelly calls Scott, who had been traveling with a deer family. Informing Scott about the bear attack, Kelly also tells him to come back.
During a search of the mountain, a female ranger stops for a break at a waterfall. Deciding to soak her feet and finally taking off her clothes and showering in the waterfall, she is unaware that the grizzly bear is lurking under the falls and she is attacked and killed. Kelly recruits the helicopter pilot, Stober, to assist in the search. Flying above the forest, they see what they believe to be an animal, only to discover the naturalist Scott adorned in an animal skin while tracking the bear. Telling them all of the bears are accounted for and this specific bear is unknown to the forest, Scott informs them that the animal they are looking for is a prehistoric grizzly bear (a fictional Pleistocene Epoch Arctodus ursus horribilis) standing at least 15 ft (4.6 m) tall and weighing between 2,000 to 3,000 lb (0.91 to 1.36 t). Kelly and Stober scoff at the notion.
At the busy lowland campground, the grizzly bear tears down a tent and kills a woman. Kelly once again insists on closing the park, but Kittridge still refuses. The attacks are becoming a national news story and, to counteract this, Kittridge allows amateur hunters into the forest. Now a team, Kelly, Stober and Scott are disgusted by this development. Later, a lone hunter is chased by the grizzly bear, but he manages to escape the animal by jumping into a river and floating to safety. Later that night, three hunters find a bear cub that they believe is the cub of the killer grizzly bear, so they use it as bait for the mother. However, the grizzly bear finds and eats the cub without the hunters even noticing. Scott thus concludes that the grizzly bear must be a male, as only male bears are cannibalistic. Kelly assigns fellow ranger Tom at a fire lookout tower on the mountain. However, he is attacked by the grizzly bear. The animal tears down the tower and kills Tom.
Kelly and Kittridge continue to argue over closing the park. Frustrated by the politics of the situation, Scott sneaks away to track the grizzly bear on his own. On the outskirts of the national park, a mother and her young child are attacked by the grizzly bear. The mother is killed while the child survives, albeit severely mutilated. Stunned by this development, Kittridge finally allows Kelly to close down the park and ban all hunters.
Stober and Kelly now go after the elusive grizzly bear alone, setting up a trap by hanging a deer carcass from a tree. The grizzly bear goes for the bait, but suddenly retreats. The men chase the animal through the woods, but it easily outruns them. When they return, they discover the grizzly bear tricked them and took the deer carcass anyway. The next day, Scott, tracking on horseback, finds the remains of the deer carcass and calls Stober and Kelly on the radio. He plans to drag the deer carcass behind his horse and create a trap by leading the grizzly bear towards them. However, the grizzly bear ambushes Scott, killing his horse by ripping its head off with one swat of its massive paw, and knocking Scott unconscious. He subsequently awakens a short time later to find himself alive, but half-buried in the ground. Just as he finishes digging himself out, the grizzly bear returns and kills him.
Kelly and Stober discover Scott's mutilated body and, in despair, return to the helicopter to track the grizzly bear from the air. They soon spot the grizzly bear in a clearing and quickly land. The grizzly bear attacks the helicopter, swiping at the craft and causing Stober to be thrown clear. The grizzly bear kills Stober before turning on Kelly, who frantically pulls a bazooka from the helicopter. Before the grizzly bear can reach him, Kelly fires the bazooka at the grizzly bear, killing him in a large explosion. For several seconds, Kelly sadly stares at the burning remains of the grizzly bear before walking towards Stober's mutilated body.