Or does it just kill everyone.

@consolemaster001:There is one version that has a mind of its own. In Superman #175 - Joker: Last Laugh: Doomsday Rex Doomsday came to Earth having developed sapient emotions and intelligence. He went after President Lex Luthor and Superman had to try and stop him. In fact, Superman actually managed to defeat this version of Doomsday for a second time by exploiting his newfound emotions of a fear of dying again along with this version of Doomsday being much weaker than the previous incarnations. It's a good story and a really great fight between Superman and Doomsday. Hope that helps!

If by sentient, you mean SAPIENT, then yes.

@lvenger: Thanks !

About to say this, good call!

There's a boatload of information on his Wiki Page here on the Vine.

@hewhosees: Fine I'll edit it in :P

@lvenger: Didn't the Doomsday during "In the Name of Gog" have emotions?

I call cowcrap on DC's writing about the earlier forms of Doomsday not having a mind. He did feel pain when Superman broke one of his protruding bones. How can one that is mindless feel pain?!?!?! And the laugh... He goshdarn laughed! What the frat?!?!?! Ok, I may be too nitpicky and it is, in fact, fiction. But I still call BS on their logic.

@kenbukaiten: Yeah he did. He lost it at the end in order to return everything to normal hence why Doomsday in Infinite Crisis was back to his usual self.