Shuichiro Oishi (大石 秀一郎, Ōishi Shūichirō?) is a fictional character in the anime and manga The Prince of Tennis. His name is spelled Shuichiro Oishi in the English manga, and it is spelled as Syuichirou Oishi in Roman characters in the Japanese version of the TV show. It is spelled "Syuitiroh" in some artwork, probably because the "chi" hiragana technically belongs to the "t" row.
In the fourth character popularity poll for the series run in Weekly Shonen Jump, Oishi came in 8th place.