Siegfried "Fritz" Flesch (March 11, 1872 – August 11, 1939) was an Austrian sabrefencer who competed in the late 19th century and early 20th century. Flesch was Jewish.
He returned to Olympic competition at the 1908 Summer Olympics, and again participated in the individual sabre event. After winning his first round pool, Flesch was eliminated from the competition in the quarterfinals after winning only 1 of 4 bouts. He finished in 24th place.