Magazine copy editor. Not reporter, or publisher, or photographer – copy editor.
Dentist: “Eversmile, New Jersey” (Daniel Day-Lewis)
Insurance underwriter: “Double Indemnity” maybe? Did he do any underwriting?
Waiter: “Waiting” (Ryan Reynolds comedy)
Printing press operator: not a film, but there’s Gutenberg! The Musical! I’d be surprised if there weren’t a film out there about Gutenberg, though.
[QUOTE=garygnu]
I don’t think I’ve seen a movie with an animator as a character. Hell, game testers just got a movie, where’s mine?
[/QUOTE]
Young Warriors. Featured some pretty trippy animation, too.
[QUOTE=Yllaria]
Sewage treatment plant operator. Although they’re called wastewater treatment plants or wastewater reclamation facilities in these more delicate days. (And I do admit that there is often more industrial wastewater than actual sewage coming into any given plant on any given day.)
[/QUOTE]
Close to this would be Kenny, in which the central character’s profession is renting out and installing portable toilets. It’s a very funny movie, but I don’t think it’s known much outside Australia.
Optometrist. Very common profession, yet somehow not very well represented in movies, at least among lead roles.
I daresay there are very few films about musical orchestration. Not composers, conductors or musicians, but orchestrators.
[QUOTE=Trunk]
Was Robin Williams a Pharmacist in that creepy movie, or just a clerk at a pharmacy that developed pictures?
That would be a pretty widely-practiced profession without ever having much of a movie role.
[/QUOTE]
One Hour Photo. He wasn’t a pharmacist. His character worked in the photo lab, developing the pictures.
[QUOTE=Bayard]
Maybe auto mechanics? They turn up to move the plot along, but I don’t know of any movies that featured one prominently.
[/QUOTE]
Trees Lounge. Except Steve Buscemi’s character was out of work most of the time.
[QUOTE=Beadalin]
Insurance underwriters. I’m sure there’s a rich vein of drama to be mined there, too, but Hollywood is too blind to see it.
[/QUOTE]
Double Indemnity featured an insurance agent and an insurance investigator (played respectively by Fred MacMurray and Edward G. Robinson) as pivotal characters. Also, Guy Pearce’s character (Leonard Shelby) in Memento was an insurance investigator who quit due to short-term memory problems. I don’t know if those examples are close enough for you.
[QUOTE=Beadalin]
Insurance underwriters. I’m sure there’s a rich vein of drama to be mined there, too, but Hollywood is too blind to see it.
[/QUOTE]
Double Indemnity.
Edit: NDP beat me to it. Forgot about Memento.
Insurance adjustors are represent the female leads in both versions of The Thomas Crown Affair.
[QUOTE=Siam Sam]
…Forgot about Memento.
[/QUOTE]
Ha!
[QUOTE=The New and Improved Superman]
Magazine copy editor. Not reporter, or publisher, or photographer – copy editor.
[/QUOTE]
[QUOTE=ArchiveGuy]
Insurance adjustors are represent the female leads in both versions of The Thomas Crown Affair.
[/QUOTE]
And in the anime Trigun the female leads Meryl Stryfe and Milly Thompson are employees of the Bernardelli Insurance Society.
[QUOTE=Beadalin]
Insurance underwriters. I’m sure there’s a rich vein of drama to be mined there, too, but Hollywood is too blind to see it.
[/QUOTE]
Not an underwriter, but there is a movie by Atom Egoyan called The Adjuster. Is that close enough?
[QUOTE=The New and Improved Superman]
Magazine copy editor. Not reporter, or publisher, or photographer – copy editor.
[/QUOTE]
Drew Barrymore’s character in Never Been Kissed is a copy editor, although, I think, for a newspaper.
[QUOTE=Siam Sam]
Double Indemnity.
Edit: NDP beat me to it.
[/QUOTE]
Who beat you to it? <casts furtive glance upthread>
[QUOTE=Bayard]
Maybe auto mechanics? They turn up to move the plot along, but I don’t know of any movies that featured one prominently.
[/QUOTE]
In Benny and Joon, Benny (Aidan Quinn) and his best friend are auto mechanics.
How about a historian?
[QUOTE=Aholibah]
How about a historian?
[/QUOTE]
If that includes archaeologists, there’s practically an entire subgenre of fedora-ed, whip toting historians in the “Action” section of your local movie store. 
I think there’s only been one movie that starred a technical writer. If memory serves, the movie was called The Technical Writer. That’s a title that’ll bring them in.