I’ve probably seen you on the N-line dozens of times without knowing who you are. Are you Guy with Glasses? Girl who once wore a peach shirt? Hot Asian chick? Man with Garbage bags of Cans? Lesbian number 6? Guy with red glasses? Man with hand in pants? Old asian man? Other old asian man? Guy from North Carolina, he hates gay people, he’s from North Carolina, you think you’re better than him, he’s a red neck, he’s from North Carolina, you think you’re better than him, he’s from North Carolina? or guy who looks like Jesus if he was Indian.
Celebrity Hunt 
As for the OP, last Sunday when I flew home Dom Irrera was on my flight. And I made him laugh. 
Wow, Tars, that’s some subway ride you take… And you know, I knew many types just like that from my days riding the LA busses. I don’t miss the LA busses.
Also being from L.A., I have seen my fair share of celebrities in various places.
I saw “Harold and Maude”'s Bud Cort at the Glendale Galleria. Saw several other character actors (don’t know their names, but one guy played a teacher on “Wonder Years” – but not Ben Stein, the other guy) at the Galleria. The stars hang out at the Galleria, I guess.
Ray Wise (of “Twin Peaks”) was a customer in the store where I worked.
Saw Charles Nelson Reilly and Sam Waterson on the road at various times. (I think Reilly was driving down Sunset, Waterson was in Century City somewhere.)
Saw one of the kids from “The Waltons” (all grown up) in Westwood.
An actor named Peter Barton (he was semi-hot in the '80s and early '90s, I think) almost ran me down on his bike going down Hollywood Blvd.
Saw Harrison Ford shooting “Blade Runner” in downtown L.A. (when they were shooting in the Bradbury Building).
Several actors went to my art school. (Peter Falk used one of the studios to do his Life Drawing.)
At the Renaissance Faire, Billy Campbell (from “Once and Again” or whatever that show is) showed up unannounced and played in an abbreviated version of “Taming of the Shrew”. No one knew who he was, and I was at a distance, but I kept on thinking, “Damn, he’s really good. And doesn’t he look like that Billy Campbell guy?” And sure enough, it was him! Pretty cool.
Saw Tom Petty in the airport.
Met the guy who plays the ominous bald guy in the wheelchair at one of my art show openings. Turns out he was the husband of a fellow student!
Met the girl who played the German War Bride in the '90s series “Homefront”, she was taking classes at the same school I was. She was nice.
A fellow student in my pottery class often brought her daughter in with her. (It was a night class, the daughter looked to be in her early teens.) Turns out that the girl was the sister of Giovanni Ribisi, and she herself is also an actress. (I’ve since seen her in a few things, more grown up now.) At the time her mom was taking this pottery class, her brother, Giovanni, was starring in the Randy Quaid / Jonathan Winters show “Davis Rules”. When the mom found out that I was a huge Jonathan Winters fan, she invited me on the set. Alas, the show was cancelled before I could go. But I do remember one thing—the mom was a damned good potter.
Oh, there are many more stories I could tell. Many, many more.
OK, I left out an important detail: The ominous bald guy from the NBC series “The Prentender” That helps, doesn’t it?
Pretender. Pretender. It’s just been one of those days.
Gee whiz, guys! This is a subway thread. Then we can have an elevator thread. Then a walking down the street thread. Then a bus thread…
“It helps to pass the time…”
I’ve met various famous and semi-famous people (mostly classical musicians) in professional contexts, but I’ve only had a few proper “celebrity spottings”.
Not quite the subway, but I was almost knocked over by John Tavener in Victoria Station as he swept by. He’s very tall. I’ve spotted Amanda Barrie from Coronation Street in a Covent Garden wine bar. And I’ve sat virtually elbow-to-elbow with Ramon Tikaram from This Life (and the movie Kama Sutra) in a rather cramped cafe in Camberwell.
CBCD: There aren’t really any subways in L.A. L.A. is a motor vehicle city. And, conicidentally, a lot of celebrities live in L.A. You don’t want to have us L.A. people feel left out, do you? Of course not!
Sorry L.A. We can’t all have what we want. No subway, no celebrities in the subway response. It isn’t personal. You can start a “New Yorkers I have seen on Rodeo Drive” thread. I’d be left out. So it goes. 
Oh piffle. This thread clearly discriminates against the subway-challenged.
I saw sumo wrestler Dejima riding the subway a few years ago. He was sitting on one of the benches giving an interview to someone.
I’m thong-bikini clad roller skating Indian Headdress wearing guy. My wife is the woman with the rabbit who hangs out by the Wells Fargo ATM on Irving and rasps “Spare Change!!”
If that’s not your sig, it ought to be.
A little too self-congratulatory for me, but thanks!