Semen I. Dvoirys is a Russian chess Grandmaster. Born on May 2, 1958, he earned his Grandmaster title in 1990. Prior to this, he was awarded the International Master title in 1985. Dvoirys has participated in a multitude of chess competitions across his career.
He won the Russian Championship in 1995. He has also performed well in several international competitions. His achievements include winning the tournament in Beer Sheva in 1990 and 1991, Moscow in 1995, Voronezh in 1997, Kishinev in 1998 and St. Petersburg in 2006. He played in the FIDE World Chess Championship 2004 but was eliminated in the second round by Sergei Rublevsky.
Dvoirys is also known for his work as a chess teacher. He currently coaches the Kazan Women's Team, which won the Russian Women's Team Chess Championship in 2011 and 2013. He also regularly contributes to the '64 - Chess Review' magazine. He was Sergey Karjakin's first coach, guiding him to his early success.