Olga Tass (married name Lemhényi, born 29 March 1929) is a Hungarian former gymnast who competed in the 1948 Summer Olympics, in the 1952 Summer Olympics, in the 1956 Summer Olympics, and in the 1960 Summer Olympics.
She was born in Pécs.
Tass was married to Dezso Lemhényi (1917–2003), a Hungarian water polo player who also competed in the 1948 and 1952 Summer Olympics.