When Linda Blair did the girl in The Exorcist, they hired Mercedes McCambridge to do the voice of the devil coming out of her. And there was controversy as to whether Mercedes should get credit. I was one who thought no, she was just special effects. So when it came to Darth Vader, I said, no, I'm just special effects. But it became so identified that by the third one, I thought, OK I'll let them put my name on it.