Buzz Lightyear is a fictional character in the Disney–Pixar Toy Story franchise. He is a superhero action figure from an in-universe media franchise. Buzz is recognizable by his lime green, purple, and white space suit. Originating as a one-man band toy named Tinny, he evolved into a space ranger action figure during the development of Toy Story, a decision made by director John Lasseter. He is named after American astronaut Buzz Aldrin, the second person to walk on the Moon. Buzz Lightyear is a recurring character in all of the Toy Story franchise's animated feature films, including spin-offs. In the Toy Story films, he is voiced by Tim Allen.

Although Woody serves as the protagonist in the Toy Story filmography, Buzz is a prominent character, with their rivalry and friendship being a fundamental aspect of the story. In Toy Story (1995), unlike most of the other toys, Buzz initially believes himself to be the "real" Buzz Lightyear and comes to terms with being just a toy. In Toy Story 2 (1999), he encounters other Buzz Lightyear action figures from the toyline who similarly believe themselves to be "real", including his in-universe archenemy and father Emperor Zurg. In Toy Story 3 (2010), Buzz explores a romance with cowgirl figure Jessie, while uncovering his Spanish mode. In Toy Story 4 (2019), he finds his inner voice and bids farewell to Woody, who leaves to be with Bo Peep.

The fictional character on which the toy Buzz is based also appears in the 2000 direct-to-video film Buzz Lightyear of Star Command: The Adventure Begins and its subsequent spin-off television series, Buzz Lightyear of Star Command. In these productions, he is voiced by Tim Allen and Patrick Warburton, respectively. Chris Evans voiced a version of the character in the 2022 spin-off film Lightyear, an in-universe film exploring his origin story, with James Brolin additionally voicing Zurg, an elderly, nihilistic version of Buzz from an alternate future.

Buzz received a positive reception on the release of Toy Story. Critics have described him as a pop culture icon and the greatest or most iconic Pixar character. He was named as one of the most influential toys of the 1990s by Time. His catchphrase "To infinity and beyond" has been described as one of the greatest film quotes of all time and he has been referenced in popular culture, including song lyrics by Beyoncé and Justin Bieber. He was named the "longest-serving astronaut in space" by NASA after a Buzz Lightyear action figure spent 15 months on board the International Space Station from May 2008 to September 2009.

Toy Story originated in the 1988 short Tin Toy, an animated Pixar film about a tin toy and a baby. The film was so successful that Disney approached Pixar to develop more animated films from computer generated animation. A feature film was conceived involving a windup toy named "Tinny" who rivals a former favorite toy, a ventriloquist's dummy. Tinny was eventually converted into a spaceman and evolved through various design changes eventually transforming into Buzz Lightyear. Disney entered into the joint project with Pixar, then a young production studio chaired by Steve Jobs, for three computer-animated feature films in a $26 million deal. The Pixar team working on the project included John Lasseter as director, screenwriters Andrew Stanton and Pete Docter, and Ed Catmull. In the early 1980s, Lasseter and his colleagues created short films at Pixar using computer software that was still being designed but they had not produced a feature film. When Disney came on board with Lasseter's idea, they pushed for edgier characters. Lasseter recalled that this made them unlikeable: "The characters were yelling, they were cynical, they were always making fun of everybody, and I hated it." Worried about losing the deal with Disney, the Pixar team reworked the story concept within two weeks with the belief that toys could appeal to adults and teenagers. The new story centred around a boy named Andy, a cowboy leading a group of toys, and a space toy, and the film was greenlit by Disney. Lasseter named various influences on the story concept, including Star Wars, the space race, and buddy comedies.

The film's script went through various changes during development. The first draft was produced in March 1991 and followed Tinny, a one-man band toy, who is given to a boy as a birthday gift. The boy's family take Tinny on holiday but accidentally leave him at a gas station, where he meets the ventriloquist's dummy. From there, the two characters have to work out how to find their way back to Tinny's owners. After a series of adventures they find their way to a kindergarten playground where they are reunited with the children. By summer 1991, Jeff Katzenberg at Disney decided that it should be a buddy film in which two conflicting characters must learn to work together. In September 1991, the Pixar team drew up a new version in which the ventriloquist's dummy is already the favorite toy in the house and Tinny is introduced as its rival, which causes friction between the two characters.

Further changes to the character followed during the development. Lasseter considered a one-man band toy to be an outdated idea and decided to change Tinny to an action figure, similar to G.I. Joe. He said, "we started to analyze what a little boy would get these days that would make him so excited that he stopped playing with anything else." G.I. Joe was Lasseter's favorite character in childhood, but later Tinny evolved into a space hero similar to Major Matt Mason. This character then went through various design iterations, initially named Lunar Larry, which was then changed to Tempus and then Morph, who wore a red space suit. Finally, the dummy character was redesigned into a stuffed cowboy doll named Woody and Morph became Buzz Lightyear. Buzz was designed to be the ultimate child's toy. Lasseter recalled, "We reached back to every favorite idea we could remember. And that of course had to involve outer space". The team knew that being a space hero, Buzz's frame needed to be strong so that it could endure through many space missions, so they designed him with many holes for screws and rivets so that it was clear how he was constructed. They took inspiration from other action figures, incorporating a "karate chop action" into the arms. Buzz was also designed with pop out wings with landing lights to give children the ability to make him fly and a blinking red light bulb on his wrist to act as a laser. A button was included on his chest, which when pushed, provides digitised audio. The lime green and purple color scheme in Buzz's design was created by Lasseter while sketching the character and was chosen as an apology to his wife for working late; lime green was the favorite color of Lasseter and purple was his wife's favorite. The appearance of television actor Ed Kemmer was also an inspiration for Lightyear. Kemmer played Commander Buzz Corry in Space Patrol, one of the first science-fiction series on American television.

Buzz Lightyear was named in honor of Apollo 11 astronaut Buzz Aldrin, the second person to walk on the Moon. The film producers thought that Aldrin had "the coolest astronaut name". Aldrin acknowledged the tribute when he pulled a Buzz Lightyear toy out during a speech at NASA. Aldrin did not receive any endorsement fees for the use of his nickname. In 2009, he admitted to being exasperated by Disney using his name for the character: "You don't want to tangle with Disney, the friend of children. You don't want to challenge their lawyers – for sure, you're going to lose."