I guess for me it would be Ringo Starr.
I worked with him in a TV series on PBS 20 years ago.
In my wrap party photo with him, I had a beer ...but his drink of choice (at the time) was CocaCola and VVVSOP brandy (in a styrofoam cup!).
On a more serious note, the month after we wrapped production he went into rehab (I wasn't responsible) and he has managed to stay clean and sober ever since. Kudos to him for that.
By the way, he was a really great, sweet guy, great to be with...and just about what you would expect given his general WTF image and attitude. A really nice guy.
It was, to say the least, quite a rush to have the opportunity to work with him. A high point in my career, to be sure.