The widowed Doctor Crusher juggles the responsibilities of raising her son alone while also serving as Enterprise's Chief Medical Officer. Crusher, along with her later husband, had been acquainted with Captain Picard long before joining its crew.
Blind since childhood, LaForge uses his impressive technical knowledge as Enterprise's Chief Engineer. He originally joined Enterprise as helmsman, LaForge is promoted in TNG's second season.
While endeavoring on his personal goal of being more human, Data is indispensable to the Enterprise, serving as its second officer and chief of operations.