This refers to films that concern themselves with larger than usual sized animals and insects. These are almost always seen as going on the rampage and are thus Monster Movies. Regular sized animals that appear in genre cinema are covered under Animals Attack Films. Dinosaurs are certainly giant-sized animals but get their own entry because they are not enlarged beyond their normal size.
The most famous and endearing of all giant animals is King Kong (1933) who roared his way onto screens, fell for Fay Wray and met his end on the Empire State Building and has made many screen appearances since.
The major iteration of the Giant Animal film came during the Atomic Monster fad of the 1950s. Although not all giant animals were atomic in nature, plentiful giant ants, spiders, scorpions, crabs, leeches, grasshoppers, shrews, octopi and gila monsters ran across the screen.
The 1970s Nature’s Revenge and Animals Attack cycle saw another wave of giant animals. Since then, we have seen sporadic individual revivals of the genre, principally of the giant bug variety and a number of others among the CGI monster fad of the 2000s/10s.