Darmen Sadvakasov (born 28 April 1979) is a Kazakh chess grandmaster, a five-time national champion (2001, 2003, 2004, 2006, 2007) and a former world junior champion.
Sadvakasov was awarded by FIDE the titles of International Master (IM) in 1995 and Grandmaster (GM) in 1998 as a result of his victory in the World Junior Championship. He tied for first at Bali 2000 and the 2003 Samba Cup. In 2004 he won the Politiken Cup in Copenhagen on tiebreak score over Leif Johannessen and Nick de Firmian. In 2007 he tied for 1st–8th with Hikaru Nakamura, Alexander Shabalov, Varuzhan Akobian, Zviad Izoria, Victor Mikhalevski, Magesh Chandran Panchanathan and Justin Sarkar in the Miami Open. Sadvakasov also won matches against Viktor Korchnoi in 2003 by the score 5–3 and former World Champion Anatoly Karpov in 2004 by the score 4.5–3.5.