Gintoki Sakata (Japanese: 坂田 銀時, Hepburn: Sakata Gintoki) is a fictional character and the protagonist of the manga and anime franchise Gintama created by Hideaki Sorachi. Gintoki's name serves as part of the basis of the series' title. He is introduced as a former rebel samurai who lives in a fictionalized version of 1860s Japan after being invaded and transformed by aliens. Gintoki once fought in the Joui (rebel) war until a tragic event where he was unable to protect what he was fighting for, leading to him instead establishing "Yorozuya Gin-chan" (万事屋銀ちゃん)" (with Yorozuya (万事屋) literally meaning "worker of 10,000 jobs"), choosing to make a living as a freelancer for hire in Edo. Eventually, Shinpachi Shimura and Kagura choose to stay and work with him, forming a found family. Across the series, more details about Gintoki's past are revealed leading him to encounter former friends as enemies. As the main character, Gintoki has appeared in most of the episodes of the anime series, as well as in other media related to the franchise, including the film and all of the spin-off video games and original video animations.

Sorachi created the character after suggestions of his editors of having silver-haired samurai. He was originally going to be based on Hijikata Toshizō, the vice-captain from the Shinsengumi special forces. However, Sorachi changed his mind as he did not want the main character to be working in an organization and further remodeled his design into the present one. In the anime series Gintoki was voiced by Tomokazu Sugita, who enjoyed his character. For the English release of the first movie, he was voiced by Chris Patton, whereas in the Gintama° episodes Gintoki was played by Michael Daingerfield; later, Roly Gutiérrez dubbed him in the first anime series. Shun Oguri portrays him in the live-action films.

Gintoki's character has received a positive critical response from various reviewers and publications for manga, anime, and other media, although his characterization in some story arcs has been criticized. When he once parodied a Japanese politician in 2016, manga publisher Shueisha faced controversy. Gintoki has remained highly popular among Gintama fans, ranking first in numerous popularity polls. Merchandise based on Gintoki has also been released, including figurines.

While brainstorming on the name for a manga, Hideaki Sorachi's editor commented, "Do you think a silver samurai would be cool?" This inspired Sorachi to create the main character after deciding the series should be named Gintama. Sorachi's initial plan for his first major series was to center it around a fictionalized version of the Shinsengumi, mostly to ride off the hype for Shinsengumi!, a Japanese drama starring idol actors as the famous Japanese special police force. However, Sorachi's version was planned to be as unrealistic as possible; his force included both men and women possessing bizarre traits that were nothing like the original Shinsengumi, and that would seep into many of the characters that would be part of his eventual manga. One of the characters from this set was a silver-haired man who was to be the representation of prominent member Hijikata Toshizō. Sorachi particularly liked Hijikata and wanted this character to be the hero of his series despite the lack of similarities with the real Hijikata.

While Sorachi loved the design he created for his silver-haired Hijikata, he could not draw out his character or figure out what he would do in the series. He considered dropping the character and his editor nearly forced him to give up on him just as the original Shinsengumi concept was falling apart. Eventually it was decided that the silver-haired character would be an original lead character, while the Shinsengumi would be portrayed as comedic foils. Quickly giving him the nickname of "Gin-san", the original concept of the silver-haired Hijikata was shattered and Sorachi recreated the character from the ground up into the lazy-eyed freelancer he would be in the series. The concept behind Gintoki's character is that he is a strong person who does not belong to any organization and tends to disregard rules. Although Gintoki was roughly based on Sakata Kintoki, Sorachi did not intend Gintoki to be a descendant of Sakata. Unlike common heroes within manga series, Gintoki does not undergo character development. This is connected with the character's background as several things in his life changed due to the Amanto invasion and wishes some things not change.

For the anime series, Gintoki has been voiced by Tomokazu Sugita in Japanese. When learning he was selected to voice the Gintama's main character Sugita wanted to show off to fit the character. However, he later took a bigger view on Gintoki's character; understanding that Gintoki lives with a lot of people's support, Sugita changed his mindset when voicing the character. In the English dub of the first movie, he is voiced by Chris Patton, while Michael Daingerfield voices him the Gintama° series.

Gintoki Sakata is a freelancer former samurai living in an era where aliens known as the Amanto have come to Earth after the Joi War, a battle in which the latter defeated the former. As a child, he was taught by Shoyo Yoshida, with his classmates being two of his future Joi allies, Kotaro Katsura and Shinsuke Takasugi. Shoyo was unjustly accused of trying to raise an army, which resulted in his capture, with Gintoki and his friends entering the Joi War to rescue their teacher. During that period, he was known as the "White Demon" (白夜叉, Shiroyasha; "White Knight" in English dub) due to his silver hair and white coat he wore in battle, which, combined with his impressive capabilities as a swordsman, made him famous among his comrades and struck fear into Amanto. During a time in the Joui War when he, Katsura and Takasugi were captured by Tendosho, under orders by Sada Sada, Gintoki was forced to execute his master without any choice before his master's final bidding to him right in front of his comrades' eyes.

After his master's death, Gintoki chooses to open a freelance business where he could handle matters his own way, while continuing to live by his own samurai code. In his job, he gets two employees, the samurai apprentice Shinpachi Shimura and the alien girl Kagura, and comes to have a close relationship with both of them. The group often have problems to pay the monthly rent for Otose, Gintoki's landlady whom he swore to protect after eating the food offerings meant to her husband's grave.