Mater in Cars 2 is subjected to Break the Cutie when he realizes that everyone else sees him as a laughingstock and a buffoon. Yet after an apologetic reassurance from his best friend Lightning McQueen, he soon returns to his regularly cheerful and optimistic disposition.
The titular character from Disney's Cinderella. She puts up with the demanding work her stepmother and stepsisters bullies her to do constantly, all with a cheerful smile and a pleasant attitude. It was only when they tore her dress and destroyed any hopes of her going to the ball that Cinderella broke down.
Anna from Frozen keeps a cheerful attitude throughout the movie. It's only when she is on the brink of death and betrayed by the man she loved that she loses her sunny disposition.
Joy, the mental personification of well, joy, in the Pixar film Inside Out. All the more appropriate, since she's voiced by Amy Poehler, of Parks and Recreation fame. It's deconstructed in that her outlook tends to be shortsighted rather than beneficial in the long term.
Sing has Buster, who is unflappably optimistic, even in light of the looming repossession of his failed theatre. Somewhat Deconstructed here, as he comes across more as intentionally disconnected from harsh reality than looking on the bright side of things. It takes the theatre's literal collapse to finally break him, leaving him in a Heroic BSoD until the other characters re-inspire him.
The titular character of Snow White and the Seven Dwarfs has been forced into slavery, almost killed by a mercenary and sent out alone into a dark and unfamiliar forest. Yet she doesn't complain or cry much and always picks herself up again.
Trolls: Poppy is very close to the actual Trope Namer in that she admits to Branch she knows life isn't all cupcakes and rainbows but she likes to believe most of it is and focus on the good things.
Vanellope of Wreck-It Ralph suffers a great deal of discrimination and out-right bullying for being a glitch. Despite being looked down on by the other racers and being forced to live in a hovel in a hidden area, she remains cheerily optimistic. The only times she falters are when somebody threatens her car, and thus her dream of racing.
Lady Sue from Akira Kurosawa's Ran. And it frightens Hidetora. His armies killed her entire family after she was sent to him as a political hostage. Her response: becoming a nun and forgiving him. It would be so much easier for Hidetora if she just hated him.
Annie, the 1982 film, when she's in the orphanage ... she just keeps thinking about tomorrow! And her sunny attitude is contagious and transformative.
In Cannibal! The Musical, this is Played for Laughs with Swan. When his companions are complaining about having no food and being weary and lost, he suggests building a snowman via cheerful song and demonstration. Even after one of his annoyed companions shoots him in the head, he still has a smile on his face.
An odd subversion in Cecil B. Demented: Raven is a Satanist, yet remains upbeat and perky, even as her fellow Sprocket Holes are being picked off left and right. If one didn't know better, one might question her grip on reality.
The titular heroine from the Swedish film Du Är Inte Klok, Madicken ("You're out of your mind, Maggie!"), is this, much more then in Astrid Lindgren's books the film is based on.
The title character of Ed Wood is constantly upbeat and optimistic about his movies, declaring that every film take is "perfect" even when glaring errors pointed out to him. He constantly believes that his next film will be a smash hit despite the overwhelming evidence to the contrary and rarely lets his spirits dim. Tim Burton claimed he wanted to make the movie through Wood's eyes, showing his sincere love for movies despite his utter lack of talent. The darker parts of his life are glossed over due to this.
Hairspray: Tracy Turnblad is infectiously optimistic, happily championing the desegregation of the Corny Collins Show. Even though there are times that she has doubts that she can succeed, she never gives up, and in the end, most of the cast is with her. "You Can't Stop The Beat!"
Played for comedy in Monty Python's Life of Brian, in which a crucified man tells Brian to keep his spirits up and closes out the film with a jaunty musical number, "Always Look on the Bright Side of Life."
Nomi Malone in Showgirls is a more believable and seemingly more cynical version of this trope. Nomi carries a knife, appears street savvy and effectively confronts a truck driver for hitting on her. However, she is shown to be ultimately trusting, to her detriment, leaving her luggage in his car to be stolen. Throughout the film she is betrayed for her trust. The callous Las Vegas show director Tony Moss mysteriously refers to her more than once as looking like a "Pollyanna", the first time for no apparent reason, the second time possibly due to her dress (though this still gives us no clue as to why he would name her as such).
Delmar from O Brother Where Art Thou is a male example. As Pete raves that now he won't get out of prison until he's 84 years old, Delmar blithely says, "Well, shoot. I'll only be 82."
In Ant-Man Scott Lang's best friend, former cellmate and sidekick Luis comes across this way thanks to his opening scene, where the two are reconnecting after the year between Luis being released from jail and Scott's release:
Scott: Hey, how's your girl, man? Luis: Ah, she left me. Scott: Oh. Luis: Yeah, my ... mom died, too. [Beat; Scott gapes in awkward silence] Luis: And my dad got deported. [More silence] Luis: But I got the van! Scott:[quickly] ... It's nice! Luis: Yeah, right?!
Eva Braun in Downfall, to a pathological and creepy degree. Seemingly living in total delusion, she's carefree as the Third Reich crumbles around her. Like Hitler ordering counterattacks to units which have long since been wiped out, Eva asks people to visit shops which have already been bombed out and abandoned, and throws parties while artillery shells land into buildings around them. In a private moment with Traudl (the viewpoint character), she admits that she knows the Nazis have no hope, but she doesn't care, she's still happy.