Probably The Blues Brothers at about a dozen times, if that. I’m not really a movie rewatcher, though. I almost never see a movie more than twice.
My (probable) top five (I’ve never counted the number of viewings):
To Have and Have Not (1944)
War of the Worlds (1953)
Rio Bravo (1959)
Kelly’s Heroes (1970)
Miller’s Crossing (1990)
I have a three-way tie for first place.
Pulp Fiction
A Simple Plan
Jackie Brown
Probably the original Terminator Trilogy, as a conglomerate.
Dirty Dancing - at least the last dance. For a while, it was being aired almost daily on some channel and we always seemed to turn it on just as Baby was brought out of the corner. 
The Big Chill - saw it on the first date with my husband and I don’t know how many times I’ve seen it in the last 35 years.
El Dorado/Rio Bravo - c’mon - they’re essentially the same movie. I can’t count how many times I’ve sat thru them thanks to my spousal unit.
I was on a **Chicago **kick for a while there - watched it lots and lots.
Treasure of the Sierra Madre, that great parable of life.
Close seconds: To Have And Have Not, Beat The Devil (yes there is a common thread here).
Wow, I screwed that up. A Simple Plan is an OK movie, but I meant Blood Simple for the list.
Alll the Star Trek movies. Many times each.
The movie I’ve seen the most times in an actual theater where I had to pay admission and everything - Star Wars
The tape/DVD that I bought and watched the most times - Airplane!
The movie I’ve seen on TV the most, even to the point I’ll actively look for it, but never actually paid money to see - tossup between Citizen Kane and Casablanca.
oh, yeah, I have to add the kaiju contingent, especially since I watched the (original, un-dubbed, Japanese version of) Rodan over the weekend.
**Godzilla/Gojira
Rodan
King Kong vs. Godzilla
Mothra
**
Not to mention the Cheap Monster Movies. I think that Chiller Theater on WPIX in New York must’ve simply owned several of them, but I also watched of Creature Feature, Supernatural Theater, Milion Dollar Movie, and The Big Show/4:30 Movie:
**The Cyclops
The Cape Canaveral Monsters
Curse of the Faceless Man
Monster on the Campus
World Without End
The Monster that Challenged the World
The Giant Behemoth
The Killer Shrews
**
It’s not as if I watch these al the time as an adult, but I watched them a LOT as a kid.
As a kid who loved comic books, I had a VHS tape of the Keaton-and-Nicholson Batman movie. I also had a VHS player. I also had no other VHS tapes.
You can see where this is going, right?
Only one vote for Rocky Horror Picture Show?
in rough descending order of frequency:
Lord of the Rings: Fellowship of the Rings, and some fewer times for each of its successors (Mrs. Charming and Rested watches them regularly but we don’t usually make it through the whole trilogy).
The original Star Wars, with fewer times for each of its successors. (I still haven’t seen all the prequel films.)
Shaun of the Dead
The Princess Bride
Indiana Jones: Raiders of the Lost Ark (The Last Crusade follows closely behind; Temple of Doom is way behind).
Up
When Harry Met Sally (Another favorite of Mrs. Charming and Rested)
Groundhog Day (or did I already say that?)
The Wizard of Oz (inescapable as a child. I’ve never loved it that much).
Gone with the Wind
Mulan (at my wife’s encouragement. If I counted the times she has just listened to the songs from the DVD, this probably goes to No. 1).
Rocky (my sister loved this movie)
Hocus Pocus (the Mrs. again, although I’ve learned to like it)
Shawshank Redemption and Titanic (always on back when I had cable)
Off the top of my head, going back to my childhood:
***The Dam Busters
The Great Escape
The Guns of Navarone
The Great Race
101 Dalmatians
Mary Poppins
It’s a Mad, Mad, Mad, Mad World
The Wizard of Oz
The Producers
Star Wars
Casablanca
Treasure of the Sierra Madre
The Sea Hawk
The Adventures of Robin Hood
Objective: Burma
Captain from Castille
Double Indemnity
Pulp Fiction
Jackie Brown
From Russia, with Love
On Her Majesty’s Secret Service
The Dirty Dozen***
Gotta get in some Westerns here, too:
***The Good, the Bad, and the Ugly
For a Fistful of Dollars
For a Few Dollars More
Blazing Saddles***
One Flew Over The Cuckoo’s Nest, by a mile.
(It’s also the book that I always return to.)
As a child of 80s, they used to replay The Beastmaster and The Clash of the Titans(the original one with Harry Hamlin) repeatedly. Some people joking referred to TBS as The Beastmaster Station. So overall, I probably seen those two movies those two movies the most. Other films I watched repeatedly as child include Willy Wonka & the Chocolate Factory(the one with Gene Wider) and The Wizard of Oz.
As an adult, I’ve probably watched the Star Wars films the most followed by the Terminator films and first Matrix film. Other films I’ve seen repeatedly include No Country for Old Men, Logan, Superman, Superman II, and The Dark Knight.
As for TV shows, I probably watched The Simpsons, Futurama, and Law & Order the most followed by Star Trek: The Next Generation, Star Trek: Deep Space Nine, and Star Trek: Voyager.
I have seen every episode of Star Trek: The Original Series, but frankly I have a hard time re-watching it do to the cheesy special effects and acting.
A lot of these movies I have seen many times. Star Wars, Fellowship of the Ring, Casablanca, Shawshank Redemption, Spinal Tap…
But in the late 80s during one of my summers home from college I managed a store for a small mom & pop video rental chain (remember those?). We had a TV at the front that we would play movies on all day, usually recent releases. All summer, six days a week, I put Better Off Dead with John Cusack in the rotation. So I saw that movie at least 40 or 45 times that summer (and a couple of times since then). So that is the winner, hands down.
“I’ve been going to this high school for seven and a half years. I’m no dummy.”
The original King Kong. When it was the featured movie of the week on Million Dollar Movie when I was a kid it would be on every night during the week and three times a day on the weekend. I would try to watch every showing. I’m sure I’ve watched it far more than any other movie. (I would watch other monster movies over and over too, but not as religiously as that one.)
The Wizard of Oz - every year when growing up
Twister! - at the start of tornado season
Groundhog Day - at least I think I’ve seen this before
Meet Me in St. Louis - during Christmas, and
A Christmas Story - ditto
Star Wars - of course, but just the original one
most of the Marx Brothers movies
I don’t know. It’s probably Blazing Saddles. I’ve watched that several times.