The Xenon Sentinel - what was supposed to protect the galaxy - a failed experiment at Space Tek, a security and military robot manufacturing company that works for Galactic Arms, a weapon manufacturing company.
One day, in Sector 12, deep within the Zephyr Nebula, one scientist in Xenon Facility, one of Space Tek's many factories, were experimenting...
"I've finally done it! I've found a way to splice human DNA with robot technology through bionic engineering!" exclaimed Professor O'Riley, running down the hallway to the Tek Overseer's office. With great enthusiasm he opened the door in front of him. "Come look at this! I've done it! I've really done it! Follow me to my lab!" The Overseer followed O'Riley to his lab. As he opened the door, he looked around and saw a truly terrifying sight - a half man, half machine with dormant red eyes laid out on a table, blood on the floors and notes tacked to bulletin boards in a messy, nonchalant fashion.
"What the hell is this O'Riley..."
"Oh, you'll love it, sir! I call it: The Xenon Sentinel. Has a nice ring to it, yeah?"
"Professor, I believe you've gone mad."
"Ohh no no no... That's not it at all sir... See, this marvelous creation of mine was built and programmed to protect!"
"O'Riley, listen to me and listen to me carefully. Another stunt like this, and you can say goodbye to your job!"
"Wait! Sir!"
The Overseer left and slammed the door behind him.
"Ohh we'll show him!"
With great rage, the Professor flipped the switch on the back of the robot's head and it sprung to life, or back to life, i should say.
"Kill!" O'Riley shouted.
The Sentinel's started growing bright red as it drew two identical blades from it's back.
"Yes! Yes! Kill! Kill everyone!"
The Sentinel obeyed it's orders and struck down the Professor. With his last breath he whispered: kill...
The Xenon Sentinel went on a mass killing spree, killing all living organisms in its way.
After years of a straight rampage through galaxies, The Xenon Sentinel arrived in the galaxy Cubore, and made its way to the only planet there: Minecraft.
If you ever see the Xenon Sentinel in your world... there is no escape... Nowhere to run or hide...
Just. Death.