Good movies with improvised dialogue

When watching the movies Humpday and The Girlfriend Experience, I was struck by how real the dialogue felt in those movies in a way I hadn’t really seen on screen before. I later found out that both movies relied on improvised dialogue. That is, the director maps out key plot points that should be hit during each scene but let the actors figure out how to convey those points and react to others on the screen.

I’m wondering what are other movies that similarly use this technique for this effect?

Spinal Tap?

If you liked Humpday, you might also enjoy Your Sister’s Sister. It’s also directed by Lynn Shelton and stars Mark Duplass. Many of the Duplass brothers films utilize improvised dialogue.

Best in Show

Secrets and Lies

Bubble used this technique, but it felt anything but real. I only watched it all the way through so I could counter anyone who said “How can you say it’s bad if you didn’t watch all of it?”

Goodfellas? The Spider scenes in particular?

All of Christopher Guest’s mockumentaries.

Bill Murray apparently improvised all of his dialogue in Tootsie.

Apparently there were large chunks of American Hustle that were improvised, including the big fight between Christian Bale and Jennifer Lawrence. I thought it was an excellent movie.

District 9 had a good portion of it improvised.

I’ve heard everything from “some” to “all” of it, I’m sure the truth lies somewhere in between

I’ve read that Topsy-Turvy was created in this way. Not sure if it counts, though, as much of the dialogue was improvised in rehearsals, and not as it was being filmed.

ETA: in the perplexing final episode of The Prisoner, the actor playing “The President” actually wrote much of his own dialogue, right there on the set, as the script hadn’t been finalized.

Robin Williams improvised a lot of the material for the Genie in Aladdin, which must have made the animators happy.

It didn’t bother the animators; contrary to what Mrs. Doubtfire portrays, they animate after the voice tracks are complete, for obvious reasons. It did piss off the writers though, who discovered all their lines were credited to Williams (he was ad libbing, but not everything).

Much of the action and the dialogue of The Blair Witch Project was improvised.

Almost every word from Bill Murray and Chevy Chase in Caddyshack were improvised. Harold Ramis would just give them a vague idea of how the scene should go and they’d wing it. There is a great documentary about the making of the film that shows up periodically on one of the high-numbered channels. I saw it a couple of weeks ago late at night.

Talladega Nights was largely improv.

Exactly the film I intended to post. Brenda Blethyn is extraordinary.

I think virtually all of the dialogue and much of the action was improvised.

Doesn’t Mike Leigh improvise most of the dialogue in his films?

Pretty much every John Cassavetes movie.

The Zak Penn movies Incident at Loch Ness and The Grand- both good movies and both of which I learned about here on the good ol’ SDMB.
MAS*H was largely improvised which infuriated screenwriter Ring Lardner, Jr., who apparently didn’t know how little of his writing made it into the film until he watched at the premiere. Apparently even winning an Academy Award for the screenplay didn’t console him much.