The Librarian, first film to feature a librarian
A Very Good Young Man, first film to feature a male librarian
Notable: The main character’s profession was changed from brass bed factory worker in the play to librarian in the film
The Lost Romance, first film to feature a librarian with glasses and a bun (the Spinster Librarian image begins!)
Notable: “Old lady foureyes!” In the film’s opening scene, two small boys shout this as public librarian Lulu Smith (Barbara Stanwyck) walks down the street.
No Man of Her Own, first film to feature a librarian in undergarments
1933 & 1940:
First films to feature a librarian saying, “Shush!”
The Seventh Victim, first horror film to feature a librarian
Pickup on South Street, first film to feature an African-American librarian
Source: Several items of trivia in this post I gathered together while reading The Image of Librarians in Cinema, 1917-1919, by Ray Tevis & Brenda Tevis, 2005, a great source for information on reel librarians.