Undersecretary

[Sarah]

A secretary who is subordinate to the chief secretary; anassistant secretary; as, an undersecretary of the Treasury.

[Tanya Shivari]

a person who works for and has a slightly lower rank than the secretary (= person in charge) of a government department:

[Mark Zuckerberg]

A subordinate official, in particular (in the US) the principal assistant to a member of the cabinet, or (in the UK) a junior minister or senior civil servant.