Akiba Rubinstein
He originated the Rubinstein System against the Tarrasch variation of the Queen's Gambit declined: 1.d4 d5 2.Nf3 c5 3.c4 e6 4.cxd5 exd5 5.Nc3 Nc6 6.g3 Nf6 7.Bg2 cxd4 8.Nxd4 Qb6 (Rubinstein - Tarrasch, 1912). He is also credited with inventing the Meran variation, which stems from the Slav defence.