Buck is the second oldest of the apatosaurus children and the false antagonist in The Good Dinosaur. Poppa Henry saw his egg moving and he grabbed a stick and hit Henry with it, and his parents announced: Hello Buck.
"Buck is Arlo’s brother: they’re the same age, but Buck is bigger, stronger and a little rambunctious. He likes to tease his fearful brother as often as he can—and Arlo is an easy target. Buck’s size, strength and confidence allow him to do things that Arlo can’t imagine doing—like ripping a tree out of the ground with his teeth."
- Buck's original name was "Forrest" and he was going to be voiced by Bill Hader, but this was changed due to being leaked.