John J. Marachuk was a colonist who resided in the terraforming colony Hadley's Hope on LV-426.
During the initial Xenomorph infestation on LV-426, Marachuk was found within the Atmosphere Processor with a facehugger latching onto his face. Marachuk was rushed to the colony's medical lab where doctors tried to surgically remove the facehugger before it implants the embryo into Marachuk. Dr. T. Biggs attempted to remove the facehugger surgically, but was killed after making a single incision on it that caused him to be sprayed with the facehugger's organic acid across the face and throat. Though the medical technicians were able to remove the facehugger, Marachuk died shortly after the removal due to traumatic shock and poisoning. Ellen Ripley and the remaining SulacoColonial Marines later came across Marachuk's medical report when they took shelter in the same medical lab.