Dux (Latin for "leader") was also the name for a Roman military commander; usually, a general who commanded multiple legions without also being a governor. It was often a prefix for dux bellorum (literally, "leader of wars") or dux provinciae (literally, "leader of a province"). It is the source of the modern duke, and is often Anglicized as such. See also Dux Britanniarum.

Dux is a title awarded to the top graduate in some schools, particularly in Scotland, Australia and New Zealand.

Dux was a Swedish subsidiary of Philips, originally an independent company that produced radios in the 1970s.