Sacagawea and her infant son, Jean Baptiste Charbonneau, are the only two non-presidents who appeared on U.S. coins as of June 2014. The pair appeared together on the face of the $1 gold coin. Also, Susan B. Anthony appeared on $1 dollar coins from 1979 to 1999.
In addition to those two well-known coins, the U.S. Mint also released an Alabama quarter in the 50 States series that featured the image of Helen Keller on the reverse side in 2003. Additionally, Benjamin Franklin appeared on the U.S. 50-cent piece from 1948 to 1963, when he was replaced by John F. Kennedy. Finally, there are a number of commemorative coins that feature Americans who were not presidents, including an ongoing series of First Spouse commemorative coins honoring presidential spouses and their accomplishments.