Really mining the memory banks here but I believe it was Bye Bye Birdie in Atlanta at the Cinerama. Mary Poppins and Sound of Music came later but Birdie was first and it had something to do with a premiere or something. Special kind of thing went with a group. I was just a little kid.
My parents took me to the drive in to see Star Wars when I was 4. At the time I got scared by the vast desert of Tatooine (much scarier than Darth Vader), and I turned around and watched the screen across the way so I wouldn’t have to look at it.
Now of course, I’m geekily happy that this is my first movie memory.
Similarly, mine is The Jungle Book, but that was released 8 years before I was born, so it must have been a re-release or maybe one of those special kids’ showings. My older brother and sister took me and we ate Fox’s Glacier Mints, which, for some reason, was the main snack at that cinema along with Highland Toffee.
And wow, this thread is showing a really wide spread of ages.
The Sword in the Stone. I was something like four or five.
1954, Them, with James Whitmore and quite a few big f-ing ants. I was 10. Birthday party, three of us, the kid’s mom dropped us at the theater and came back later to get us. My parents didn’t go to the movies so I’m sure this is my first.
I saw E.T. in the theater when I was 6. I remember being excited because we won free tickets to another movie since our popcorn bucket had a special mark on it.
I also have a very early memory of seeing a re-release of Lady and the Tramp at a drive-in. I have no idea how old I was, I’m thinking this might have even pre-dated E.T. My sister is not quite three years younger than I am, I remember her being pretty little. We both fell asleep in the car.
I am pretty sure that would be my first movie memory as well- probably in the mid- 70s (before VCRs when lots of movies got played for years in the theaters). Next to that was Star Wars.
Nobody’s said the first film they saw didn’t have sound yet. You’d only have to be about 85 or so.
The earliest I clearly remember was “Star Wars.” I was six. I’m sure I saw movies before that but don’t recall.
My first recollection of a theatrical movie is also Billy Jack, most likely during the 1973 re-release when I was 10.
Here’s an interesting interview with the kid who played the bully, by the way:
http://popcultureaddict.com/interviews/davidroya-htm/
Walt Disney’s Song of the South, you know, Zippidy-do-dah, Brer Rabbit, Uncle Remus and all that. It had to have been in 1946 or 1947 in Bellefontaine, Ohio. I distinctly remember something about a bull chasing a little boy that frightened the daylight out of me – spent the rest of the movie on my mother’s lap to the exclusion of my little sister. I would have been four of five years old at the time.
My parents went to the drive-in and threw us in the back of the car. The movie was Elephant Walk which came out in 1954. I just remember a little, and then I fell asleep.
Or perhaps only forty-ish!
Yet another who remembers E.T. I’m sure I’d been to the movies before, but E.T. was a huge event. I remember watching it in a big old theatre, and the huge line to get in.
I think I saw Watership Down a few years before but I’m not sure. Not a good film to take a preschooler to…
The first I remember is “Around the World in 80 Days,” which came out in 1956. However, I was not born until 1958.
So, it must have been a re-release. I think I was about 4 or 5 at the time.
The earliest I can place with any certainty is The Ten Commandments. We saw it in a neighborhood theater, so it was 1956 or later, when I was 5 or 6. We got there very late (thanks, Mom!) so the first scene I saw was Moses in chains being brought before Pharaoh. Of course, at the time, you could stay in the theater and see the next showing.
I know we saw Fantasia in its re-release at about the same time, but the first time we tried to see it the lines were so long we just went back home.
I also have a very vague earlier memory of seeing Pinocchio at a drive-in during its 1954 re-release.
We didn’t see movies often when I was growing up; to this day, I prefer to watch most films at home, with the odd exception of something so full of effects that I really do want the theater experience.
The shows we did go to when I was young were always Disney films; my folks took the movie ratings VERY literally, and we were not allowed to see a PG movie until we turned 13. (This was before the PG-13 rating was added)
So I remember seeing The Shaggy DA and I think Flubber, and Herbie the Lovebug movies.
My first ‘adult’ movie I watched, with my mom: The Gooodbye Girl. LOVED IT, have had a crush on Richard Dreyfuss ever since. 
And the first time I was allowed to go to a film without my folks was to see ‘Grease’. Loved that, too. 
I remember being pre-school age, probably by a good bit, watching Gone With the Wind at a drive through. I only remember one thing and ironically that’s what I was deliberately kept from seeing: the scene where Scarlett shoots the soldier coming up the staircase, which is when somebody (I guess one of my parents or whoever was with us) put their hand over my eyes, and in fact that moment I didn’t see is all i remember of the movie. I remember somebody saying “She’s about to kill him, don’t let Jon see it…”, and later it was easy to piece together which movie it was since my family rarely attended them and remembered the re-release of GWTW. (Google reveals there was a pretty major re-release for its’ 30th anniversary, so I was probably 3.)
It’s a four hour movie and I was little so I’m guessing (and hoping for my parents’ sake) I slept through most of it. That scene was probably pretty gory by 1939 standards- if you’ve never seen it Scarlett plugs the deserter square in the face at point blank range and while there’s not close up of brain and all there is a good bit of stage blood- but of course you see worse at 8:00 p.m. on network now.
I’m pretty sure I saw movies on a home projector many times before this, but the first theatre movie I can recall seeing must have been The Man Who Would Be King, in 1977, when I was 6. Took movies a whole year or more to get out here then. Next one would have been Star Wars.