I was trying to think of the shortest movie titles, and of course immediately thought of M. How many other one-letter titles are there? (Trying to do this without checking IMDB.)
I thought of “V,” but that was a TV series. And “X” was apparently just a marketing scheme; the actual title was Malcom X. . . . and then there’s the Godley and Creme album, “L.”
Any other movies though?
π.
Dang, I’d thought of that earlier but forgot it when I wrote the OP.
how about:
$
Though, if you think about it, that could also be the longest movie title ever.
There used to be a lot of “B” movies. 
Has there been a movie released as “___________ {Untitled}”?
Ha. That’s awesome.
Am I allowed to cheat and claim the movie starring Morgan Freeman, Brad Pitt, and Kevin Spacey was called “7”?
I thought of that, but I don’t think it counts. “10” misses it by one, too. Then there’s “8½.”
I did a force search in IMDB and am pleased to report that it lists many movies with single digit titles.
Two movies have been named “1”. Three movies have been named “2.” While no movies are listed entitled “3” (there is one called “Three”) there are an amazing eight listings for “4.” There are no movies named “5” but at least one movie named “V” in the sense of the Roman number, not the letter. There is an Indonesian film called “6” though only translated; in general usage it was called “Enam,” which means “6.” No 7’s. There are two listings for “8,” and two for “9.”
As I am sure most have already guessed, all these movies are very obscure.
Gotcha beat, sort of, quantitatively: Less Than Zero
I know, I know.
Gotcha beat, sort of, quantitatively: Less Than Zero
I know, I know.
And if Seven can be shortened to 7, then “dot the i” with Gael Garcie Bernal
I don’t remember if it was a movie, or just a sci-fi series, but V.
S^G
ETA: Apparently, it was just a tv series.