Tom Petty and the Heartbreakers 8 or 9 times. And, for everyone that says “I don’t like his voice” or “I don’t know any Tom Petty songs”…GO! I promise 75% of his concert will be songs you know from the radio and he puts on a great show. That’s what I said the first time and I only went because a friend of mine didn’t want to drive to the show and back alone (a two hour drive each way). Didn’t think I’d know a single song and I ended up able to sing along with almost every one of them.
That’s sad, they put on a great live show. I saw them for those five times over the period of less than a year, and then they disbanded. Murray, the bass player, plays with Great Big Sea now, so I get to see him from time to time. 
Damn, I forgot about Riot Fest. That’s TWO times I missed him when I could have attended. I’m starting to question my fandom.
Clutch - saw them a lot back when they were first getting started, playing tiny clubs around DC, and every time they’ve come back to play the area. I don’t know the exact number, but it’s probably somewhere between 3 and 4 dozen times.
Blue Oyster Cult and Aerosmith. Not so much that I was a big fan but because when they were coming up they opened for a lot of bands here.
Actually I’m much more of a BOC fan than Aerosmith.
And **Jian **has a popular radio show in Canada (and famously interviewed Billy Bob Thornton a few years back.)
There cannot possibly be people here who have not heard of Tom Petty. 
Riders in the Sky—My wife loves them and to be honest, I am getting to really enjoy them. They shout hellos to me from the stage now and comment on my taste in music and baseball teams.
(before my wife entered the picture) Jefferson Airplane in all their different inceptions.
Not that they haven’t heard of Tom Petty but they’ll say “I don’t know any Tom Petty songs”. I think most people (that are 30+) are surprised to find out how many Tom Petty songs they actually do know.
I have seen Live 12 times. 13 if you count Ed K’s solo act.
Mott the Hoople at least 4 times. (Maybe 5: it was a long time ago.)
Genesis and Elvis Costello
Oddly enough, I think Cowboy Mouth is the only band I have seen in concert more than once. I have seen them more than 10 times although some of those when they were first getting their start when I was in college in New Orleans. They are an exceptional concert band.
Another Mouth fan! Excellent! 
(They are, indeed, an exceptional concert band: their live shows are quite amazing. It’s been too long since I’ve been to one.)
Wait…the Wootens played a wedding!? Before they were famous, presumably.
Riders in the Sky six or seven times.
The Bobs (do they count?) 4 times in one weekend.
Styx 3 times. Kilroy tour, twice with Lawrence Gowan and Glen Burtnik.
Alice Cooper twice: Nightmare Returns, second year of Psycho Drama tour.
George Thorogood twice. First time with Simon/Blough/Carter second time with addition of Chrismar.
Apart from some local bands I think my top two are REM and Radiohead with six times apiece.
I’ve seen the Steve Miller Band 4 or 5 times. I think that’s tops for me.
Yeah, the Kinks a whole bunch of times, going back to the 70s (hey, I’m older than you). Can’t even remember how many times. Also Ray Davies solo a few times (three or four?), in the 90s and 2000s.
I’ve seen a whole bunch of performances by the Metropolitan Opera, going back as far as the 70s again, but I too think this is restricted to rock and pop bands.
Stray Cats, about a zillion times, but that’s cheating – they were the house band at a more-or-less local bar before they got famous.
I was lucky in where I wisely chose to grow up – a lot of now-famous or semi-famous bands were pretty much local bands that I saw a lot. The Ramones and Marshall Crenshaw. Robert Gordon. Black 47. Some others that I’ve probably forgotten.
No official count, but it would have to be Widespread Panic. Not because I was a Spreadhead, but because I was a club kid at UGA when they were starting out, and they played lots of gigs at my favorite bars. The Indigo Girls are probably second, for the same reason. ( I loved living in Athens, and being able to see truly good live music all overthe place, almost any night of the week. Everyone from Arlo Guthrie to Wendy O. Williams and the Plasmatics to Living Color. And REM, of course.)
Outside of that time span, Chicago, KISS, Aerosmith, and AC/DC are all tied at two.