Robert Siska (born December 1, 1942) is an American former tennis player and motorsport driver.

A left-handed player from San Francisco, Siska made the singles third round of the 1959 U.S. National Championships as a teenager and competed on the international tour through the 1960s.

He featured in the Wimbledon singles main draw four times and won his first round match in 1963, over Ion Țiriac.

Siska, who worked in real estate, financed his own career in motor racing after tennis.

His best race result in the Atlantic Championship was a 10th-place finish (from 35 cars) at Laguna Seca Raceway.