Named after Johannes Kepler - German astronomer (1571-1630).
Kepler is a crater in the Eridania quadrangle on Mars. On March 25, 2006 a section of the floor was photographed by the HiRISE camera aboard the Mars Reconnaissance Orbiter. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Mars large craters are named after deceased scientists, writers and others who have contributed to the lore of Mars. Small creaters (less than 60km) are named after small towns and villages.