For those who have played the Portal games, they will know GLaDOS and who she is. For those who don't know, I'll just say she is a computer AI for a place called Aperture Science. This is a orodha of how Shadow and GLaDOS are similar.
-Both were engineered kwa science. Shadow on the ARK, GLaDOS in Aperture Science.
-Both are immortal.
-Both are artificial lifeforms
-At first, they start out evil, but turn good later
-Both brag about being immortal and having power over others
-Both were created to benefit mankind
-At one point, at least once, someone tried to kill them. The Commander and Black Doom tried to kill Shadow. Chell tried to kill GLaDOS
-Both were once thought to be dead. Shadow at the end of SA2 and GLaDOS at the end of Portal
-Both felt malice towards someone. Shadow towards Sonic and GLaDOS towards Chell