The Goat is one of Sam's animals, he appeared in Green Eggs and Ham, where Sam-I-Am tries to ask Guy-Am-I to eat that food with a goat. He is seen with a few dogs chasing a fox in the 1973 cartoon. In the Netflix series, he is a bounty hunter sent by Snerz to speed the Chickeraffe's arrival to him.
In the original book and the 1973 TV special, the Goat was just a normal animal that was harmless. Whilst in the Netflix adaptation, Goat is more of an antagonist. Which would make him the first Dr. Seuss character to be adapted into a villain.