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.
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.
William T. Riker
The ambitious Commander Riker who aspires to make captain by 35 is the Enterprise's first officer.