Sagara Sanosuke (相楽 左之助) is a fictional character from the Rurouni Kenshin manga and anime series created by Nobuhiro Watsuki.

During his introduction in the series, he encounters the wanderer Himura Kenshin, who easily defeats him and is able to convince him to stop his mercenary work and instead start protecting people.

Sanosuke appears in the featured films of the series and in other media relating to the Rurouni Kenshin franchise, including a plethora of electronic games and original video animations (OVAs).

Watsuki describes Sanosuke's visual motif by referring to his design model, Lamp, the main character of Susumu Sendo and Takeshi Obata's Mashin Bōken Tan Lamp-Lamp.

To emphasize his hate of the Meiji Government, Watsuki drew the Japanese kanji for "evil" (惡, aku) on the back of Sanosuke's jacket in the original series, but on the kanzenban redesign, the tattoo is located inside his clothes.

"[17] In producing the English dub version of the series, Media Blasters chose Lex Lang as Sanosuke's voice actor.

When writing Sanosuke's dialogue, Clark Cheng, the writer of the English dub script, noted that the character was smarter than he would have liked in the first few episodes, so Cheng tried slowly to change the character's dialogue to make Sanosuke seem less intelligent so he would be more similar to the equivalent in the Japanese version of the series.

[19] But when the revolutionary government encounters financial problems, it labels the Sekihō Army as frauds in order to "bury their promises".

[22] The destruction of the Sekihō Army and the loss of all his friends has caused Sanosuke to hate the Meiji Government and he wears the Japanese kanji for "evil" on the back of his jacket.

[29][30] Although he does not reveal his identity to his family, upon learning of their poor situation Sanosuke attacks a former Ishin Shishi who was mistreating them and the town.

[34] After a successful rescue, Sanosuke leaves Japan and travels the world to avoid being arrested for attacking the Ishin Shishi.

In the Rurouni Kenshin: The Motion Picture, Sanosuke helps to stop the samurai Takimi Shigure from overthrowing the Meiji Government as an act of revenge.

[46] In the Critical Survey of Graphic Novels: Manga, multiple writers acknowledged how both Sanosuke and Yahiko spend their time in the series searching for ways to become stronger.

[10] Chris Beveridge appreciated the fight scenes from Restoration due to how Sanosuke is presented stronger than in the original manga, making his duel with Kenshin more enjoyable.

Munetaka Aoki's acting was praised by Ko Ransom from Anime News Network, finding it faithful to the original character.

[50] Nick Creamer from the same site also noted how in the first live-action film, Sanosuke's characterization was identical to the original series as he is initially an enemy to Kenshin but later becomes his friend.

[51] On the other hand, Creamer criticized Sanosuke's portrayal in the second film as he stated that he "tends to chew the scenery in his appearances" to the point he found him less realistic.