Yeah, about this character... he's kinda like an ape, he's kinda like a dog... he's two hundred years old and he's got the genius level IQ necessary for navigating a starship and repairing cybernetic systems...
Peter Mayhew's particular genius lay in his ability to convey emotion without words, and with his face covered by a hairy mask. With merely a tilt of his head, his posture, or a sudden start, he could get across the disposition of this alien character. The audience could sense this hairy 'monster's' decency, his loyalty, the fact that he acted as the 'conscience' of his amoral partner. This particular scene from the first movie is a nice, understated example- Peter Mayhew's interaction with Harrison Ford, accompanied by merely a dubbed growl, tells you everything you need to know about the moral compasses of the two characters:
One comment that I read noted how Peter Mayhew's warmth and gravitas transformed what could have been a schlocky B-movie character into a beloved icon. While the character was tasked with providing some of the comic relief of the movie, Peter Mayhew was able to convey genuine moments of pathos, such as this scene in which Chewbacca voices his anguish as his heterosexual life partner rides off into danger to save their imperiled friend:
By all accounts, Peter Mayhew was just as kind and loyal as the iconic character he portrayed. The tributes from his co-stars all portray a lovely man, as did his director. The stories of fans and convention workers all say the same- he was the star who would give a kind ear to a fan, the guest of honor who would have dinner with 'the help' after the event. The pictures of him horsing around with the other cast members are heartwarming, and he was genuinely devastated by Carrie Fisher's death:
Again, we lost one of the Good Guys, who was one of the good guys. I can think of no better tribute to Peter Mayhew's acting ability than this bit by Rian Johnson:
RIP Peter Mayhew. To create a beloved character with warmth and humor is a testament to any actor’s spirit. To do it under a half ton of yak hair takes a true legend. ❤️❤️— Rian Johnson (@rianjohnson) May 3, 2019
But beyond his acting ability, there was the real man, and the tributes to him that have been coming in from all over the galaxy also testify to his True Legend status. Luminous beings are we, and Peter Mayhew shone brightly.