The Rogue was the final product of the gene splicing experiments being carried out by Professor Kleist at Charon Base under Project Chimera. Although Kleist had achieved significant success genetically engineering tame Warrior hybrids, he encountered severe setbacks when attempting to create a hybrid Queen, including many attempts that were born horribly deformed, eventually perishing as a result of their mutations. The breakthrough came when Kleist incorporated human DNA in the hybridization process, using genetic material taken from John Cray. The result was the Rogue, an enormous and hugely powerful male Xenomorph "king" that it was hoped would act as a tame counterpart to naturally-occurring Queens.