|Full name||Semyon Isaakovich Dvoirys|
|Born|| 2 November 1958
Zhmerynka, Ukrainian SSR, Soviet Union
|Peak rating||2615 (October 2004)|
Semyon Isaakovich Dvoirys (Russian: Семён Исаакович Двойрис; born 2 November 1958) is a Russian chess Grandmaster.
In 2001, he tied for 1st-2nd with Alexey Korotylev at Geneva Open. In 2010, he won the Izmailov Memorial in Tomsk and tied for 1st-4th with Sergei Yudin, Pavel Smirnov and Sergei Iskusnyh at Pavlodar. In 2011 he came first in the Lev Polugaevsky Memorial in Chelyabinsk.
Dvoirys helped Russia 1 team to win gold at the 2014 European Senior Team Chess Championship in Sibenik, scoring 6.5/9 on first board.