Henrik Larsson, Chris Sutton, John Hartson, Neil Lennon, Paul Lambert, Lubomir Moravcik, Alan Thompson, Shaun Maloney, Didier Agathe, Bobo Balde, Johan Mjallby...pretty much everyone who was at Celtic in 2003 (besides Lubo)
Regularly see Martin Kelly out and about, he was 2 years above me in school.
Last time I saw him was when he was on the bus into town after Liverpool had beaten Arsenal earlier this season, had a bit of a chat with him and his mates, still seemed pretty down to earth (suppoose he must be if he still goes on nights out in Warington). Also, was stood behind him in the queue in the Co-op once.
Met Gareth Farrelly too, as he played for Warrington Town a couple of years back.
In the 90's my brother played for the Chelsea academy for a long time - about 8 years or so? So once during the week they'd train on the astroturf up at Battersea Park (usually just the youth team) and the weekends they'd be training at Harlington (then they moved to Cobham at the end) and every time I'd have to go there with whichever of my parents took him because I was too young to stay at home on my own. I ended up meeting basically the entire team of the time (Dennis Wise, Guilet, Poyet, etc). Seeing them every week, though, I really couldn't care less, and got back to reading my Gamesmaster magazine (Loved it!). My mum actually ended up chatting to Michael Dubbery for ages whilst he was injured, every week they'd have a half hour natter over a bacon sarnie in the cafe area. Wise used to have a little ladder'y thing to help him down from his land rover, aha.
Liverpool team - went on the team bus to get my shirt signed after a game. Not that I support Liverpool mind, my cousin's team had just played a match against them. Stevie G was a decent enough bloke I guess, but a bit abrupt - scouse?
Obviously my cousins and their various team mates over the years.
Ummm, I'm Catalan and my family are Barca socios so... Yeah, pretty well most of the players and staff
One of the club doctors/medics, Emilio, is really nice! He is rather small and is like a sweet old grandad-type dude!
Wayne Rooney - back when he was a kid playing for the Everton junior team; was always out and about in Liverpool.
Met David Silva in Gran Canaria once - I was visiting family out there and he's kinda like the local hero but really down to earth at the same time!
I don't know who else right now, I'll edit if there are more I remember though
Edit: Umm, don't know how I forgot the most well known one but... Tío Pele Obviously not my actual Uncle, but my real Uncle used to play with him and I went to nearly every game for years. The only thing I remember though is a) he is tall! :O and b) he was really good with kids, like the sort of person who you feel comfortable with?