Uxas was the name that Darkseid was given at birth, living his life as a member of the Apokolips royal family.
At this point I imagine some of you may be confused by the mention of Uxas and how it relates to Darkseid, so I will clear that up quickly.
After breaking out of a chrysalis that formed around him after this process, he gave himself the “god-name” Darkseid, and began his iron fist rule of his home planet.
After years of desiring to kill his sibling, Uxas finally got his chance when Drax was engaged with a connection to the Omega Realm, and he wound up taking power from the extra-dimensional reality instead.