Chocolat: Due to her mother's being on the run, the narrator has one constant friend, Pontouf who is a kangaroo. It isn't until the end of the movie, after her mother decides to settle in the town, where we see Pontouf from the child's point of view, hopping away to have his own adventures. "I didn't miss him."
Jack Flack in Cloak & Dagger (1984) was the father figure to the kid whose Disappeared Dad was one of those "present but not here" types. Interestingly, it was implied that a version of him had been the father's imaginary friend as well; also, when the kid rejects Jack Flack out of horror for the real violence to which he's just been exposed, Flack starts to die, and says "I hate this part ... leaving when they stop believing." All this suggests that "Flack" does have some sort of independent existence.
It's also interesting that Jack Flack is played by the same actor as the dad, suggesting the hero that his son had always believed him to be, despite everything. The final line just tops it off: "I don't need him, anymore. Dad. I've got you."
Jojo from Jojo Rabbit has one of these in Hitler. He increasingly grows disillusioned with him over the course of the movie mostly because he befriends the Jewish girl, Elsa, his mom is hiding in their attic but also because the tide of the war starts turning towards the allies and because the Nazis kill his mother. Once his town gets liberated and “Hitler” starts taunting him about going outside with Elsa, he kicks him out of a window and says “Fuck off, Hitler!”
In Poltergeist the family briefly mistook the poltergeists for Carol-Anne's imaginary friends.
Stir of Echoes had the same problem; the family briefly mistook the ghost for the child's imaginary friend.
Likewise in Jack Frost [the family film], the snowman everyone thinks the boy is fixated on is inhabited by the ghost of his father.
Drop Dead Fred is about a girl who had her imaginary friend locked in a jack-in-the-box by her mother, and lets him back out by accident after she grows up. Apparently he still exists because Elizabeth still needs him.
How Imaginary or Not So Imaginary he really is is pretty open to debate. The film tries to have it both ways. In one scene Elizabeth is taken to a therapist by her mother, and while she's in the waiting room Fred plays with several of his own friends, who are the imaginary friends of the other children in the room. We see the scene from the perspectives of Elizabeth and the other children, and each child can only see their own friend, apparently playing with nobody.
In Fight Club, Tyler Durden turns out to be an imaginary friend.
In A Beautiful Mind, Nash's college roommate, the little girl, and the CIA agent are just a part of John Nash's imagination.
The movie Troll 2 also features the (long-dead) Grandpa Seth being mistaken for an imaginary friend of the child.
In Everything You Want, Abby, the protagonist, creates an imaginary friend named Sy as a way to cope with the emotional abandon by her perpetually traveling parents and her incapability to relate with other human beings derived from the above. Sy grows with her until adulthood and becomes her model and her perfect boyfriend. Abby is content with the situation, until she mets a classmate and begins to fall in love with a real person for the very first time...
Tomás in El Orfanato (a.k.a. The Orphanage), he is actually a ghost.
In Un Sussurro Nel Buio (aka A Whisper in the Dark), the boy's imaginary friend is the ghost of his brother who died as an infant before he was born.
The giggly, bald Cajun guy in The Machinist turns out to be a figment of the protagonist's guilty conscience. And the airport waitress/single mother the protagonist chats with turns out to be a manifestation of the mother whose son he recklessly killed with his car and fled the scene. The son of the "waitress" is a manifestation of the boy the protagonist killed.
The Amityville Horror (1979) has Jodie, a pig-like creature that's the imaginary friend of the little girl member of the Lutz family; at one point in the film the girl's mother Kathy hears her talking to Jodie in her room, goes inside and is told Jodie left through the window. Looking outside, the mother sees a demonic face with red eyes staring back at her. In the 2005 remake Jodie is reimagined as the spirit of one of the murdered members of the Defeo family, instead of a (presumably) demonic entity.
In the Kevin Costner film Mr. Brooks, the eponymous character is urged to commit his killings by "Marshall,"(William Hurt), who acts as his id, as well as an extremely close companion who both friendlily taunts him and comforts him in times of despair. Interestingly, many of Brooks' secret talents and mental skills, such as his Living Lie Detector ability and cunning attention to detail, seem to manifest especially through Marshall.
Brazilian movie A Mulher Invísivel features an imaginary lover, the "invisible woman" of the title.
Reyeb for Malik in Un Prophète by Jacques Audiard. Remarkably friendly (if mysterious) considering Malik murdered him.
Donnie Darko's "friend" Frank is considered imaginary by his doctor, even though Donnie's convinced that he's real.
In Paper Man, Ryan Reynolds plays the superhero imaginary friend of the main character, a middle-aged failed writer.
In the 1961 British film Hand in Hand, Rachel has always had a "pretend sister" and asks her opinion about everyday things.
Paranormal Activity 3 shows that the demon terrorizing Katie and Kristi initially introduced itself to Kristi as an entity named "Toby," who the rest of the family assumed to be just an imaginary friend.
The movie Sunday at Tiffany's, based on a book by James Patterson. Jane's imaginary friend Michael left her life on her 10th birthday. Twenty years later, on the eve of her birthday and her wedding, he shows up again—this time as a corporeal adult. Neither of them have any idea why he suddenly showed up out of nowhere or what his mission is. Michael falls in love with Jane, who is initally very resistant to his naiive, innocent view of her and the world. Eventually, she realizes she isn't satisfied with how her life has gone since Michael left, and that she loves him...just as he has to leave again. Or does he?
Woody Allen's character in Play It Again, Sam is just divorced and not adjusting well to being single. So in order to cope with his insecurity around women he creates an alter ego based on Humphrey Bogart.
Haunter: Lisa's little brother Robbie is often playing with his imaginary friend Edgar, who eventually appears before Lisa. It's later revealed to be the killer himself appearing as he did when he was a child, as he originally grew up in the house.
In The Spirit of the Beehive, six-year-old Ana, after watching Frankenstein and inspired by a ghost story of her sister, becomes obsessed with the idea of befriending an imaginary monster.
The Ladykillers (2004): Mrs. Munson invites the Sheriff in to introduce him to her tenant Prof. Dorr. Since the Professor is trying to keep his criminal scheme under wraps from the authorities he hides from the Sheriff under the bed, which Mrs. Munson finds very amusing. This all conspires to make it seems like the old lady has lost it and is talking to imaginary people from the Sheriff's vantage point.
In the film Parental Guidance, one of the issues Artie and Diane Decker (played by Billy Crystal and Bette Midler) face when babysitting their grandkids is that of their youngest grandson Barker and his imaginary friend Carl the invisible kangaroo, whom Barker claims tells him to do dangerous things. Later on, Barker is taught to stand up to Carl, who Barker then claims is now upset by this and is supposedly "killed" after getting hit by a car while running away.
Tully: Marlo (Charlize Theron), a worn-out mother of three including a newborn baby, hires the titular night nanny (Mackenzie Davis) to help take care of the kids and even bonds with Tully, it's implied that Tully was just a figment of a sleep-deprived Marlo's imagination to help her cope with her post-partum depression.
Jungle: At the greatest depth of his Sanity Slippage, Yossi believes that he is being accompanied by a native woman he finds abandoned in the jungle. Believeing that he is caring for someone else is enough to keep him pushing forward.
Asylum: This is what Lucy appears to be to Barbara in "Lucy Comes to Stay". At the end of the segment, it turns out that Lucy is really a Split-Personality Takeover.
In Big Driver, Tess has conversations with, and takes advice from, Doreen who is the central character in mystery novels she writes.
In A Boy Called Po, Po retreats into the world of his imagination, where he is friends with Jack, who looks suspiciously like the janitor at his school. Jack takes the form of a pirate, a cowboy, a knight, and an astronaut, and is usually asking Po for help with something.
In Daniel Isn't Real, young Luke locks his imaginary friend "Daniel" away inside his mind after Daniel prompts him to poison his mother, almost killing her. Years later, Luke lets Daniel loose, with catastrophic consequences. The film implies that Daniel is real and not a figment of Luke's imagination. Luke calls Daniel a "parasite" and Daniel tells Luke that he's been around for centuries, jumping from one host to another.
