Butler was a member of a Marine detachment sent to acquire a Xenomorph specimen for the Government. Butler later grew close to Rebecca Jorden, the "civillian advisor" of the mission to the protests of Sergent Hicks. He was one of two Marines to survive the botched mission and return to Earth, which unknown to the survivors, was overran by the Xenomorph menace.
Butler; along with Newt and Hicks would escape Earth and wound up encountering the sociopathic General Spears as one of his "guests" in his facility. Butler would later take part in the mutiny against Spears by manning the atmospheric controls for the base. Butler was unintentionally abandoned during the skirmish between Spears's troops, the rebelling Marines and the Xenomorphs. Butler's subesquent fate is unknown after the creatures overran the base.
Butler was created for a future retrieval mission for the Terran Government in the later years of the 22nd century. During his time being created Butler and the other Synthetic Marines heard a rumor of and advanced model synthetic that believed itself to be a live human being and could pass for human unless lab tests were done. Butler would later be trained as a Colonial Marine, believing it to be the closest thing to family.
In order to prepare for the mission to the Xenomorph homeworld, Butler and the other synthetic Marines were running training exercies with their new Sergent, Dwayne Hicks. Butler ran one combat simulation with his good friend and fellow squadmate Easley against Sergent Hicks. During this exercise, Easley discussed with Butler on disabling the automated turret that had them pinned down. Butler then attempted to draw the turret's fire while Easley disabled the turret. Butler then heard a grenade go off and the turret stop firing, thinking Easley stopped the turret, Butler then stood up to cheer but was shot with a paint round on his chest. Hicks, then chastised the two for how they ran the drill, and stated that in "honor" of Easley's and Butler's "deaths" that the squad would have to perform more drills.
Butler and the rest of Fox Platoon stationed on The Benedict left Earth on their 18 month retrieval mission to bring back a Xenomorph specimen for the Terran Government. Unknown to the mission's commander; Sergant Hicks smuggled a stowaway, Newt, on board before lift off and due to Colonel Stephens's unfamiliarity of the Marines under his command, he was unable to pic out the stowaway. Unlike their commander, Butler and the rest of the Marines were able to pick her out due to the platoon being well acquainted with each other. Butler was attracted to the young woman and soon would make attempts at getting close to her.
Butler started to talk with Newt and threaten his fellow Marines if they insisted that she was brought on to be Hicks' companion on board. Newt; surprised by Butler's actions, would tell him that nothing was going on between her and Hicks and eventually returning his advances. Hicks would later try to break up the budding romance between Butler and Newt by overriding his feelings with his programming to obey a superior officer's orders. Newt and Butler continued to pursue their relationship regardless of Hicks' protest. Eventually, the two snuck off to a storage area and became intimate.
Hostage and Rescue Attempt
Shortly after, an alarm went off and Butler rushed off to arm himself telling Newt to stay hidden. Butler made his way to the armory with the rest of the Marines only to find that their carbines were sabotaged and were now unarmed. Butler was captured in the ensuing fight on board and was taken hostage by the pirate forces. Bueller and the rest of the captured Marines were suited up in combat gear and loaded onto a dropship and sent to the surface of the planet's surface.
When Butler and the others made it planetside, the pirates set the Marines near a hive to be used as hosts for more xenomorphs to be used by the pirate's employer. As the Marines of Squad One moved towards the entrance of the hive, the combat androids were ambushed in their air pods by an indegnous flying species taking out several air pods and grounding one, which an android managed to escape. The android made his way to the hive entrance to be greeted by Butler and his squad. The squad disarmed the hostage with Blake getting his Plasma Rifle and Butler taking the pistol.
The squad then left the hive and proceeded to acquire more weapons arming the rest of the squad by taking out more air pods and sniping grounded androids. Bueller managed to figure out that their coms where hacked by the enemy ordered the squad to head south, but then gave a coded order to head north to the dropship. The android hostage not understanding the order, headed south and was gunned down by friendly fire. With Ramirez on point; the squad was getting close to the dropship. Ramirez decided to scout ahead and secure the fropship; little did the Marines know that the pirates rigged the dropship with a timed explosive which went off and took Ramirez in the explosion.
The squad then received a transmission from Sergent Hicks, letting them know that the pirates on the Benedict have been delt with. Overjoyed that Newt was alive, Butler was excited until the Marines received a panicked transmission from one of the crew. The paniced man was calling out for a rescue since his position was being overran by the Xenomorphs. Butler and the other Marines, following their directives that no harm could come to humans by innaction started to head to the hive to last known coordinates in the hive. Apologizing to Newt as he set out Butler told her it was something that they had to do.
The squad made their way back into the hive and noticed that the Xenomorphs were on them in waves as they made their way into the hive. In the first wave the squad lost Chin and Smith to the creatures. Leaving only himself, Blake and Mbutu; Butler and the others pressed on. Another wave of the creatures struck with one of the creatures barreling into Mbutu, pinning her down before it's head was vaporized. Unfortantely for Mbutu, the creature's acidic blood doused her face, and the Marine opened her mouth to scream to get a mouthfull of the acid. Butler, doing the only humane thing he could shot Mbutu in the head to end her suffering.
Eventually Butler and Blake made it to the hatchery in the hive and were able to find four of the crew members cocooned. When the Marines went to inspect the four they found that two of the three men and the woman were already dead from the chestbursters. Butler and Blake released the last crew member, whose egg hadn't hatched yet. As the man was freed, Hicks and Newt laneded in the spare dropship to evacuate the planet of the survivors. Happy to be leaving and to be with Billie again Butler didn't notice the Xenomorph drone that snuck up behind him. The creature then bisected Bueller at the waist revealing to Newt his secret: that he was an android. The dropship gave cover fire as Blake carried Butler's upper half to the dropship.
- In the reissues and adaptations of the Book Trilogy, Butler's name was changed to Mitchell Bueller.