sentences:  in 1978 World Gym also asked him to design a logo, and he created the World Gym gorilla logo, still in use today.In 1980, he played an uncredited role on the popular Incredible Hulk television series as the " demi hulk " a half transformed version of Bixby as a human Hulk in the episode " Prometheus ".It was a mystery that perplexed fans for many decades as to who the identity of the guest star was.