Monsters, Inc.

Monsters, Inc. is a 2001 movie produced by Pixar Animation Studios. It was Pixar's fourth computer animated movie. The movie was released to theaters by Walt Disney Pictures in the United States on November 2, 2001. It was released in Australia on December 26, 2001 and in the United Kingdom on February 8, 2002.
"Monsters, Inc." had a 3D re-release in theaters on December 19, 2012. A prequel titled "Monsters University", which was directed by Dan Scanlon, was released on June 21, 2013. A television series titled "Monsters at Work" was released on Disney+ on July 7, 2021.
Plot.
Monsters Inc. is a factory where monsters walk into the bedrooms of children at night to scare them and harvest their screams, which generate energy to power the city of Monstropolis.
The film begins when a monster named Thaddeus unsuccessfully scares a child. One of the things he did wrong was that he left the door open, which is the worst mistake a monster can make because a child can walk out of the room and into the Monsters Inc. factory. According to Mr. Waternoose, the CEO of Monsters Inc., human children are toxic and even a single touch can kill a monster. For this reason, he needs scarers that are tough and frightening, such as Sulley. Sulley is the top scarer at the company, thanks to his assistant Mike. Randall, at second place, will work hard to take the top spot away from Sulley.
Sulley and Mike get up that morning and head to Monsters Inc. for work. In the lobby, he sees his girlfriend Celia Mae, the receptionist at the company. This means she answers calls from other monsters who work there. Mike wishes Celia a happy birthday and wants to take her to a fancy sushi restaurant called Harryhausens.
Mike heads to the scare floor to begin his work day, and Sulley meets him there. After the monsters have been scaring for a while, Mr. Waternoose tells Jerry, the scare floor manager, told him that 58 doors were lost that week because children are becoming less scared of monsters. Therefore, the company is not producing enough energy to continue operating and Mr. Waternoose must find some other way to get the energy needed to save the company. Shortly after that, all the doors are returned to the door warehouse and all the monsters go home.
Mike rushes out of work to go out with his girlfriend, so he forgets to finish his paperwork. Sulley goes back to the scare floor to get his paperwork. He finds a door with flowers, and peaks inside. He notices a little girl, whom he calls Boo, playing with his tail. He tries to put her back in the room, but Randall appears and sends the door back to the door warehouse. Sulley places Boo in a suitcase and heads to Harryhousens to see Mike. He shows Mike Boo, but she escapes and runs around the restaurant, which led the CDA to evacuate the restaurant and decontaminate it. Mike and Sulley bring Boo home.
The next day, Sulley and Mike put a monster costume on Boo before taking her to work so that nobody will think that she is a human child. In the lobby, Mr. Waternoose tells Sulley to stop by the simulation room to show trainees how scaring should be done. Sulley and Mike go to the scare floor to see if her door is there and it wasn’t. Then, Boo runs off and Sulley looks for her. However, Mike couldn’t follow him because Celia got mad at him for ruining their birthday dinner. He tries to kiss her, but she slaps him. He then runs off looking for Sulley. Randall stops Mike and asks where Boo is. After Mike finds Sulley and Boo, they go back to the scare floor and find her door there. Mike goes into her room and jumps on her bed. Randall then captures him, sends the door back to the warehouse, and takes him to the basement.
In the basement, Randall builds a machine called a scream extractor, which he uses to harvest screams from children’s mouths. Sulley and Boo go to the basement to find Randall and Fungus using the scream extractor on Mike. Sulley unplugs the machine and Mike escapes. Randall, plugs the machine back in and notices that his assistant Fungus is using it. Mike and Sulley head to the simulation room where Sulley shows off his scaring abilities. Mike explains the situation to Mr. Waternoose, who takes Boo and promises to set things right. However, he reveals that he is working with Randall as his henchman. He kidnaps Boo and sends Mike and Sulley through a door that leads to the Himalayas.
In the Himalayas, Mike and Sulley meet a snowman monster named Yeti, who was also sent to the Himalayas. Yeti tells both of them that there is a village nearby. Sulley and Mike both go there and enter the factory through a door in one of the houses there. They go to the basement, where Mr. Waternoose and Randall are using the scream extractor on Boo. Sulley saves Boo. He breaks the machine and throws it at Randall and Mr. Waternoose. Sulley and Mike escape from Randall and head back to the scare floor to see if her door is there so that they can put her back in her room. On the way, Celia attacks Mike, slowing them down. Celia asks Mike to tell the truth about what happened or else they are breaking up. Mike tells her what happened, but she doesn’t believe him until she sees Boo. 
Mike and Sulley then ride doors through the door warehouse looking for Boo’s door, while being chased by Randall. After Randall attempts to defeat both of them multiple times, they trap him in a door that leads to a trailer. In the trailer, two people think he is an alligator and hit him multiple times with a shovel. After defeating Randall, they head back to the scare floor with Boo’s door. When they get back to the scare floor, Mr. Waternoose and the CDA are there waiting for them so that Waternoose can take Boo and the CDA can arrest Mike and Sulley. Mike distracts the CDA while Sulley and Boo escape, leading Mr. Waternoose into a scare simulation room. There, Sulley tricks Mr. Waternoose into revealing his conspiracy with Randall to kidnap thousands of children. Mike records the conversation, exposing him to the CDA, and Mr. Waternoose is arrested. Undercover CDA agent Roz allows Sulley to send Boo home, but has the door demolished.
Sulley discovers that laughter can save the company, as laughter is proven to be 10 times more powerful than screams. With that, Sulley takes the helm of Monsters Inc. as the new CEO. During the company’s first day of making children laugh, Mike and Sulley go to the simulation room to find Boo’s door put back together. Sulley enters it and sees Boo. At that point, the movie ends.
Development.
The idea for "Monsters, Inc." came during a lunch in 1994 attended by John Lasseter, Pete Docter, Andrew Stanton and Joe Ranft. One of the ideas that came out of the brainstorming session was a movie about monsters. "When we were making "Toy Story", Pete Docter claimed, "everybody came up to me and said that they totally believed that their toys came to life when they left the room. When Disney asked us to make more films, I wanted to tap into a child-like notion that was similar to "Toy Story". I knew monsters were coming out of my closet when I was a kid. So I decided monsters would be appropriate". Docter's original idea revolved around a 30-year-old man dealing with monsters (which he drew in a book as a boy) coming back to bother him as an adult. Each monster represented a fear he had, and conquering those fears caused the monsters eventually to disappear.
Pete Docter started working on the script in 1996. He completed a draft treatment in February 1997 with Harley Jessup, Jill Culton and Jeff Pidgeon. However, Sulley worked in the scream refinery before being changed to Monsters Inc.'s top scare producer. Also Boo was 6 years old, but was changed to 3 years. This was because "The younger she was, she became the more dependent on Sulley," claimed by Pete Docter. The initial story did not have the character of Mike Wazowski. Mike wasn't added to the story until in April 1998, when development artist Ricky Nierva drew a concept sketch of Mike and everyone liked it. Jeff Pidgeon and Jason Katz story-boarded a test in which Mike was helping Sulley choose a tie for work and Mike Wazowski soon became a vital character in the movie. Originally Mike had no arms, and had to use his legs as appendages, however due to technical difficulties arms were soon added. Billy Crystal had been approached to play Buzz Lightyear in the original "Toy Story", but turned down the offer. However, once he saw the film, he regretted not taking the part, and when he was approached to play Mike, he jumped at the offer. The film went into production in 2000.
One of the major breakthroughs of "Monsters, Inc." was the simulated movement of Sulley's fur and Boo's shirt. The animators would animate the characters "Bald and Naked". Once the animation was finished, a computer program aided by the "Simulation Department" would apply the hair and cloth onto the characters. If Sulley moved the hair would react to the movement just like it would in nature. The same goes for Boo's T-shirt that would produce wrinkles in the fabric. This would save the animators from animating the three million hairs on Sullivan individually.
Harryhausen's was originally going to be blown up but due to the September 11 attacks, the explosion was replaced with a plasma containment orb.
A lawsuit by Stanley Mouse alleged that the characters of Mike and Sulley were based on drawings he had tried to sell to Hollywood in 1998.