Wookey was the surname of a friend of Terry's, Ralph Wookey, and Terry thought it would be a funny in-joke to include his friend's name in the soundtrack for THX-1138. He was big, a big bear of a dog.' During the climactic chase scene in THX 1138, one of the robotic cops, voiced by actor Terry McGovern, improvises: 'I think I ran over a Wookiee back there', and thus the word was born.
According to an interview with creator George Lucas, the inspiration for the Wookiee was Lucas's dog, Indiana (whose name is used in Lucas's Indiana Jones movies): 'He was the prototype for the Wookiee.