Sidney "Sid" Phillips is one of the kids around Andy's age in the neighborhood; however, the two are never seen to interact with one another. Due to a lack of attention from his parents, especially his father, Sid is able to get away with rather destructive and sadistic behavior, torturing and destroying his and his sister's toys in various ways. His "villainous" acts have given him a nasty reputation among the toys such as Sheriff Woody and Buzz Lightyear.
Sid Phillips was created by John Lasseter for the film Toy Story. His character is based off of several different Pixar employees who would destroy their toys in strange and violent ways, an example being the melting of Green Army Men via a magnifying glass.
Lasseter has said during interviews that he is the exact opposite of Sid and acted much more like Andy when he was younger, taking great care for his toys.
In the first Toy Story film Sid is seen wearing a black skull shirt and has braces, this is when he is 11 years old. Sid is briefly seen in the third film, Toy Story 3, as a young adult who works as a garbage man. As his older self he still wears his skull shirt.
It is unknown exactly what effect the traumatic event in the first film caused on Sid or how it impacted him later in life.
Major Story Arcs
In the film Toy Story, Sid serves as the primary antagonist, a name spoken in hush toned by Andy's toys. Sid makes his first appearance shortly after the arrival of Buzz Lightyear, the fact that he was spotted home was alarming to Andy's toys due to the fact that he was supposed to be away at summer camp; however, he was kicked out due to his behavior. Sid's first major action in the film is to strap an explosive device to a toy known as Combat Carl, when the toy explodes Sid laughs maniacally and heads back into his home.
Sid is later seen at Pizza Planet where Buzz and Woody are trying to find Andy. Unfortunately for the Toys they are trapped inside a claw machine which Sid then uses, winning one of the Little Green Men as a prize he spots Buzz and Woody, using the claw to grab them as well, under the impression that they were special prizes. Sid takes these toys back to his home where he gives the Little Green Man to his dog, Scud, as a toy, who tears it apart viciously.
While Sid has the toys under his roof he performs several torturous acts, one of them including what he dubbed a triple bypass brain transplant in which he swapped the heads of two different toys, one of them being a doll that belonged to his sister, Sally, and another being a dinosaur toy that presumably belonged to him. Sid then later burns a dot into Woody's head while interrogating him about a rebel base, he would've done more damage but was called downstairs by his mother who had just finished making pop-tarts.
Sid's master plan is discovered when he recieves a large package in the mail, an explosive rocket known as the Big One. He plans on blowing up both Buzz and Woody but a rain shower delays his plans, thus giving Woody time to plan an escape, unfortunately for Buzz he was caught in a depression and played no part in gaining his freedom.
Once the weather clears up Sid straps the Big One to Buzz Lightyear and heads outside, he sets up an entire space to simulate a rocket launch, pretending to talk to an overseer through a walkie talkie. It is during this setup phase that Woody and Sid's Toys are able to put an escape plan in action, revealing themselves to Sid as being alive and traumatizing him after they swarm him. This event causes Sid to become incredibly fearful of toys, running and screaming into his home where he encounters his sister, Sally, and one of her dolls. Sid was so terrified of toys at this point that he ran from Sally after she shoved her doll in his face.
Toy Story 2
Sid isn't seen in Toy Story 2; however, he is mentioned in a speech by Buzz Lightyear in an attempt to motivate the other toys to help find Woody.
Toy Story 3
Sid makes a brief cameo on Toy Story 3 as one of the garbage men picking up trash. He sports the same clothing he wore in the first film but is much older than before. He is seen picking up the trash outside of Andy's house and then disappears for the rest of the film.
Monsters Inc. Laugh Factory
Sid appears in the Monster Inc mini-series as an unnamed child, stealing toys from various children. After he is caught by Mike Wazowski and Sulley he explains that he was trying to save the kids from the Toys, clearly affected by the events of Toy Story. The monsters ignore this and throw Sid back into his own world.
Sid later escapes back into the Monster World and teams up with Randall and Henry J. Waternoose III who promise to give Sid the door-travel technology that they use as long as he helps them gain revenge on Mike and Sulley. Unfortunately for Sid their plan for revenge fails and Sid is thrown back into the human world with the monsters hoping they've seen the last of him.