Question: Barry James O'Sullivan, an Australian politician, a former police detective, grazier, property developer and LNP executive treasurer, O'Sullivan was appointed by the Queensland Parliament to the Senate seat vacated by which Australian politician who has served as the Deputy Prime Minister of Australia?

Context paragraphs:
Neville Bonner: Neville Thomas Bonner AO (28 March 19225 February 1999) was an Australian politician, and the first Indigenous Australian to become a member of the Parliament of Australia.  He was initially appointed by the Queensland Parliament to fill a casual vacancy in the representation of Queensland in the Senate, and later became the first indigenous Australian to be elected to the parliament by popular vote.  Neville Bonner was an elder of the Jagera people.

Deputy Prime Minister of Croatia: The Deputy Prime Minister of Croatia (officially the Vice President of the Government of the Republic of Croatia (Croatian: "Potpredsjednik/ Potpredsjednica Vlade Republike Hrvatske" )), is the official Deputy of the Prime Minister of Croatia.  Article 109 of the Constitution of Croatia states that the cabinet is to be made up of the Prime Minister, one or more Deputy Prime Ministers and other cabinet ministers.  According to convention, if the governing parliamentary majority is a coalition of parties, all junior partners in the coalition will usually be given one Deputy Prime Minister in the cabinet, with their rank usually being determined by the number of MPs the party has in Parliament.  The Deputy Prime Ministers are permitted to simultaneously hold a ministerial portfolio while in office, but may also serve without holding such a portfolio.

Barnaby Joyce: Barnaby Thomas Gerard Joyce (born 17 April 1967) is an Australian politician who has served as the Deputy Prime Minister of Australia since 18 February 2016, as the Leader of the National Party of Australia since 11 February 2016, and as the Minister for Agriculture and Water Resources since 21 September 2015.  He was sworn in as Minister for Agriculture in the Abbott Government on 18 September 2013.  Water Resources was added to his portfolio on 21 September 2015 in the Turnbull Government.

Deputy Prime Minister of Singapore: The Deputy Prime Minister of the Republic of Singapore is the deputy head of the government of the Republic of Singapore.  The role of Deputy Prime Minister is the second highest post and senior Cabinet Minister in Singapore.  The holder will sometimes assume the role of Acting Prime Minister when the PM is temporarily absent from Singapore.  Since the mid-1980s, Singapore has usually had two Deputy Prime Ministers at a time.  Only Ong Teng Cheong and Tony Tan (who later became Singaporean presidents) served under more than one Prime Minister during their time as Deputy Prime Minister.

John Panizza: John Horace Panizza (24 March 1931 – 31 January 1997) was an Australian politician.  Born at Southern Cross, Western Australia, he was a farmer and property developer, and served on Yilgarn Shire Council.  In 1987, he was elected to the Australian Senate as a Liberal Senator for Western Australia.  He held his Senate seat until his death in 1997; Ross Lightfoot was appointed to replace him.

Julia Gillard: Julia Eileen Gillard, {'1': ", '2': ", '3': ", '4': "} (born 29 September 1961) is a former Australian politician who was the 27th Prime Minister of Australia from 2010 to 2013, as Leader of the Australian Labor Party.  She was previously the 13th Deputy Prime Minister of Australia, and held the cabinet positions of Minister for Education, Minister for Employment and Workplace Relations and Minister for Social Inclusion from 2007 to 2010.  She was the first and to date only woman to hold the positions of deputy prime minister, prime minister and leader of a major party in Australia.

Swedish governmental line of succession: The Swedish constitution of 1974 allows the Prime Minister of Sweden to appoint one of the Ministers in the cabinet as Deputy Prime Minister ("biträdande statsminister", also unofficially known as "vice statsminister", "Vice Prime Minister"), in case the Prime Minister for some reason is prevented from performing his or her duties.  However, if a Deputy Prime Minister has not been appointed, the Minister in the cabinet who has served the longest time (and if there are several with equal experience the one who is oldest) takes over as head of government.  Note that the person acting as Prime Minister does not do so on a permanent basis: if a Prime Minister dies, resigns or loses a vote of confidence in the Riksdag, the Speaker of the Riksdag will then confer with the parties of the Riksdag and propose a new Prime Minister, who must be tolerated by a majority of the Riksdag.  If the Prime Minister has resigned or lost a vote of confidence, he or she will remain the head of a government "ad interim" until the new Prime Minister assumes his or her office.  The only case where the governmental line of succession becomes relevant is when the Prime Minister dies (upon which the person next in the line of succession serves as the head of a government "ad interim") or when the Prime Minister is on leave or for any other reason incapable of serving, but still remains in office.  This might be compared to the Presidential line of succession in the United States, where the person next in line assumes the Presidency throughout the remainder of the term if the President dies, resigns or is impeached.

Paul Keating: Paul John Keating (born 18 January 1944) is an Australian politician who was the 24th Prime Minister of Australia and the Leader of the Labor Party from 1991 to 1996.  Keating represented the division of Blaxland in the Australian House of Representatives and served as Minister for Northern Australia in the Whitlam government and as Treasurer of Australia and the 7th Deputy Prime Minister of Australia in the government of Bob Hawke.

Barry O'Sullivan (politician): Barry James O'Sullivan (born 24 March 1957), Australian politician, was appointed a member of the Australian Senate for the state of Queensland on 11 February 2014, representing the Liberal National Party (LNP).  A former police detective, grazier, property developer and LNP executive treasurer, O'Sullivan was appointed by the Queensland Parliament to the Senate seat vacated by Barnaby Joyce, who had resigned to contest the House of Representatives seat of New England at the 2013 federal election.

Deb Frecklington: Deborah Kay "Deb" Frecklington (born 3 September 1971) is an Australian Liberal National politician who is the member of the Legislative Assembly of Queensland for Nanango, having won the seat at the 2012 state election and is the Deputy Leader of the LNP.  She was appointed Assistant Minister for Finance, Administration and Regulatory Reform on 3 April 2012 and subsequently appointed to the role of Assistant Minister to the Premier in June 2014.  Following the LNP's defeat in 2015, she was appointed to the LNP front bench as Shadow Minister for Agriculture.

Supporting paragraphs: Barry O'Sullivan (politician) Barnaby Joyce
Answer: Barnaby Thomas Gerard Joyce