"Yoshi (ヨッシー, Yosshī?, sometimes romanized Yossy in earlier Japanese materials) (IPA: /ˈjoʊʃi/) is a fictional dinosaur who appears in video games published by Nintendo. His debut was in Super Mario World on the Super Nintendo Entertainment System as Mario's accomplice (a role he has often reprised), and he later established his own series with several platform and puzzle games, including Super Mario World 2: Yoshi's Island. He has also appeared in many of the spin-off Mario games, such as the Mario Party, the Mario Kart, and the Super Smash Bros. series, as well as in other various Mario sports titles. Yoshi also appears in New Super Mario Bros. Wii as the characters' accomplice, similar to his original debut role in Super Mario World. Yoshis come in many different colors, though his original and most common color is green. Yoshi's latest appearance is in Super Mario Galaxy 2."
Source: Wikipedia, "Yoshi", available under the CC-BY-SA License.