Yoshi is a fictional dinosaur who appears in video games published by Nintendo. Throughout the mainline Super Mario series, Yoshi typically serves as Mario's trusted steed. Yoshi debuted in Super Mario World (1990) on the SNES as Mario and Luigi's steed.

Yoshi is the title character of the Yoshi series and a supporting character in the Mario franchise. He has appeared in Mario Party and Mario Kart, as well as many Mario sports games. He also appears as a playable character in the crossover fighting game series Super Smash Bros. Yoshi is a member of the same-named species, which is distinguished for its wide range of colors.

Yoshi has been well-received, with some critics noting that he is one of the most recognizable characters and one of the best sidekicks in video games. Yoshi's image has also appeared on a range of products, including clothes and collectibles.

Shigeru Miyamoto, the video game designer at Nintendo credited with inventing the Mario series, had wanted Mario to have a dinosaur companion ever since the first release of Super Mario Bros.; however, Nintendo engineers could not add such a character into the game due to the limitations of the Nintendo Entertainment System (NES). The inspiration for Yoshi can be traced back further, to the green dragon Tamagon in the 1984 video game Devil World: also designed by Miyamoto, both are green lizards that hatch from eggs and can eat enemies with their large mouth, and also emit the same noise when they hatch. During the development of Super Mario Bros. 3, Miyamoto had a number of sketches around his desk, including an image of Mario riding a horse. Takashi Tezuka, a Mario series developer, speculated that Miyamoto's love of horse riding as well as country and western themes influenced Yoshi's creation. The concept of Mario riding a dinosaur also came from the NES video game Excitebike, which featured people riding motorcycles.

Once the more powerful Super NES was released, Miyamoto was finally able to implement Yoshi into the series, putting Yoshi into the video game Super Mario World. As development of Super Mario World progressed, the team opted to set the game in a "dinosaur land", so Tezuka asked designer Shigefumi Hino to draw a reptile-like creature based on Miyamoto's sketches. Hino originally produced a design that Tezuka deemed too reptilian, and "didn't really fit into the Mario world", so he encouraged the designer to create a "cuter" character. According to Hino, Yoshi's tongue attack was originally conceived as Yoshi sticking out his tongue in surprise when Mario hit the back of his head. This was later "passed off" as Mario merely pointing forward to signal Yoshi to stick out his tongue. Alongside the individual Yoshi, Super Mario World also introduced other members of the Yoshi species, characterized by their variety of colors.

Yoshi proved to be popular in this debut, which caused the next game in the series, Super Mario World 2: Yoshi's Island, to focus on the Yoshi species. At Miyamoto's prompting, Hino landed on the idea of using Yoshi as the main character of a platforming game, with the goal of being more accessible than previous games in the Mario series. To give the gameplay a more "gentle and relaxed pacing", the levels lack time limits and feature more exploration elements than previous games; Yoshi's flutter jump also makes him easier to control in the air than Mario. In this game, he is responsible for Baby Mario, which leads him to Bowser's Castle, where he is reunited with Baby Luigi. Yoshi successfully pulls the twins together just in time to go home after beating a huge Baby Bowser.

The version of Yoshi seen in the live-action Super Mario Bros. film was realized using a 0.91-metre-tall (3.0 ft) animatronic dinosaur. Yoshi was designed in the film by Dave Nelson. The animatronic had nearly 60 meters (200 ft) of cable and hundreds of moving parts inside of it and was controlled by nine puppeteers. The body was cable-controlled, while the head was radio-controlled. Nelson described the overall process as being "difficult." The creation of Yoshi was handled by a company independent from the filmmakers.

Yoshi first appeared in the 1990 Super Mario World, as a rideable companion to Mario.