I've met a couple of South African celebrities, even taught some (who became celebrities as adults - I'm a primary school teacher) and got one guy's autograph for my mom since she was a fan (Scot Scott). I have some autographs of American celebs that other people got for me, either at cons or after plays or whatever.
My favourites are Stan Kirsch's. I have four or five of his autographs. (Stan played Richie in the Highlander TV series.) Absolutely everybody mentioned me to him at cons, and so all my autographs say things like, "The Ultimate Flag Waver!" or, "Thanx for being such a great fan!" and are signed, "Love, Stan."
The writers of the show even named a character in an episode after me (Marina, in the episode "The Ransom of Richard Redstone" - the character with my name kidnapped Richie and tied him to her bed!!!) because I was so notorious for being Richie's "Chief Flag Waver".
I also have Avery Brooks's autograph, Leonard Nimoy's, Michael O'Hare's (he played Sinclair in Babylon 5) and Paul Gross's (Fraser from Due South). I don't collect autographs, though - people just get them for me because they don't weigh a lot unlike if I asked for souvenirs.
I kind of wish I'd asked another local celeb (Loysio Mangena) for his autograph, if only so I could put it up in my class - when I taught him, he was quite a naughty kid - but he's gone on to be a successful actor and rap artist. And the first time I saw him after he became famous, I responded something like, "Loyiso, is that you? Give me a hug! What are you doing with yourself?" ... By this stage he had already been in a TV show and had a CD out. But I didn't know that, and he was happy to give me a hug and fill me in on his life. But whenever I see a pic of him in a magazine, I flash back to this 12 year-old kid who never sat down when I told him to!