Chewbacca was envisioned as a mix between “a monkey, a dog, and a cat.”
The original script of Star Wars described Chewie in the following way:
“…An eight-foot tall, savage-looking creature resembling a huge gray bush-baby-monkey with fierce ‘baboon’-like fangs. His large yellow eyes dominate a fur-covered face…[and] over his matted, furry body he wears two chrome bandoliers, a flak jacket painted in a bizarre camouflage pattern, brown cloth shorts, and little else
The Chewbacca costume was made from real yak and rabbit hair, making it extremely hot and difficult to wear for actor Peter Mayhew. It got so steamy in there, the eyes of the costume kept coming unglued and rolling out of Chewbacca’s face. They finally figured things out by Return of the Jedi and installed a water cooling system, allowing Mayhew to stay in costume for hours.