The Big Guy is an Apatosaurus that lived in Land of the Lost.
The Big Guy was a large, long-necked Apatosaurus. He had a long and small head, along with a whip-like tail. Big Guy appears frequently around the Porter's, mostly browsing on the vegetation, either at big lakes or at the Porters' treehouse. Big Guy once helped Annie Porter down from a tree when Kevin Porter took away a ladder, and saved Tasha from the Sleestaks. Big Guy can sometimes be seen at the lake. In "Life's A Beach", Big Guy is seen with another Apatosaurus, possibly his mate.
- Big Guy is thought by some fans to be Dopey, the infant Sauropod from the original series, as an adult.