I worked in backstage security for awhile about 10 years ago. Met a lot celebs like rockstars and wrestlers, a couple of actors.
The nice ones I met:
-HHH, Shawn Michaels, Kane, Tommy Dreamer, Goldberg, Shannon Osbourne, Jason Newsted (talked with him for like a halk hour), Jennifer Love Hewitt (except for her bodyguard, he wasn't too thrilled), Michael Berryman, Danielle Harris, Gunnar Hansen, Mark Hamill. They were all pretty pleasant.
The meanest one I met by far: Marilyn Manson. He trashed backstage room during Ozzfest and was surrounded by his entourage of bodyguards that kept pushing people out of the way. One of the Ozzy's bandmates had his girlfriend backstage and almoat got trampled by them. I pulled her out of the way and he looked like he wanted to beat the crap out of him.
The one that baffled me: Ozzy Osbourne. I said hello to him and said something like, "Isepepttemdora (?)" I'm still trying to figure out what that means...