Girl friday

[Justin Bieber]

A [go to girl]; a [female] who will [help] you get things taken care of; a female you can rely on when you are in need of extra assistance; a female who acts as a jack of all trades and is capable of doing almost anything; a girl you can count on when you are overwhelmed with your own chores and the duties must be done; a girl who does most of the leg work on a project, but never takes (or gets) credit.

[Luis Fok]

A [go to girl]; a [female] who will [help] you get things taken care of; a female you can rely on when you are in need of extra assistance; a female who acts as a jack of all trades and is capable of doing almost anything; a girl you can count on when you are overwhelmed with your own chores and the duties must be done; a girl who does most of the leg work on a project, but never takes (or gets) credit.

[Gregory]

a female office worker who does different types of work