Cassius is an unusual last name too for all people. (2000 U.S. Census). Presented below is the baby name popularity of Cassius for boys. Cassius reached its highest position of #684 in the U.S. in the 1880s, and is at #704 currently.(2014 Birth Statistics). Below is a graphed analysis of the popularity of Cassius and corresponding names.resented below is the baby name popularity of Cassius for boys. Cassius reached its highest position of #684 in the U.S. in the 1880s, and is at #704 currently. (2014 Birth Statistics).