President of the Senate (Australia)
The position is provided for by Section 17 of the Constitution of Australia. The Senate elects one of its members as president at the start of each new term, or whenever the position is vacant. This is usually—though not necessarily—a member of the party or coalition that holds the most seats in the Senate. The largest party in the Senate is not always the governing party, as government is determined by the House of Representatives. The President of the Senate and the Speaker of the House of Representatives may consequently be from different parties.
Department of Defence (Australia)
The head of the Department, who leads it on a daily basis, is the Secretary of the Department of Defence (SECDEF), currently Greg Moriarty. The Secretary reports to the Minister of Defence, currently The Hon. Christopher Pyne MP, following appointment by Prime Minister Scott Morrison in August 2018.