Cassius \c(as)-sius\ as a boy's name is pronounced KASH-us. It is of Latin origin. Possibly "empty, hollow". An old Roman family clan name. Shakespeare's Julius Caesar depicts Caius Cassius as politically ambitious. In modern times, Cassius Clay was the birth name of the heavyweight boxing champion Muhammad Ali.

Cassius has 3 variant forms: Cash, Cass and Cassio.

For more information, see also the related name Cassian.