Elizabeth Bouvia did. The courts believed HER, didn't they?
She consented to die but didn't believe it would be a horrible death. We can figure that out because as soon as she tried it, she said, "Uh oh, this isn't what I thought it would be. This is no fun at all and I QUIT!!!" And they couldn't starve and dehydrate her after that. Could we say that her first directive was "MISinformed consent"?
At last report (at least the last one I've seen), she was still alive. Hooray for Elizabeth.