According to most, the term "Renegade" is just a generic term for any monster that has crossed into another world through a Gateway. For some reason, such monsters gain a strange power when this happens and they become much more powerful. Furthermore, Renegades cannot usually be defeated by anyone unless they are from the Renegade's original world themselves.
In another world of the Infinity, however, Renegades were actually the warped forms of people who were wiped out due to the process of world fusion. The Order in that world was able to encase these Renegades in some form of armor, utilizing them as extremely effective shock troops.