Frederick Helsher Rath Sr. (born September 1, 1943) is a former Major League Baseball pitcher who appeared in 8 games for the Chicago White Sox during the 1968 and 1969 seasons. He threw right-handed.

Rath, who attended Baylor University, was drafted by the White Sox in the 4th round of the 1965 amateur draft and made his major league debut 3 years later. Following the 1970 season he was traded to the California Angels for John Purdin, but never appeared in a major league game again.

Rath's son, Fred Rath Jr., also had a brief major league career, appearing in two games for the Colorado Rockies in 1998.