Denis Vincent Napthine AO (born 6 March 1952) is an Australian former politician and veterinarian who served as the 47th premier of Victoria from 2013 to 2014.

After graduating he attended the University of Melbourne, where he studied to be a veterinarian, undertaking a bachelor's and then a master's degree in veterinary science.

Under Napthine's leadership, the Liberal Party did poorly in the polls and made no significant electoral inroads on the ruling Labor government.

Shortly before the 2002 state election, Shadow Health Minister Robert Doyle challenged Napthine for the leadership of the Liberal Party.

"During September 2014 Napthine and Daniel Andrews told the Australian Christian Lobby that they would allow a conscience vote should a private members bill to repeal section eight of the Victorian abortion laws be introduced.

[16] On 11 June 2014, following a Labor move to expel Shaw from Parliament that was defeated on party lines with the support of the speaker, Napthine's government successfully moved a motion that resulted in the Members of the Legislative Assembly suspending Shaw for a period of eleven days, fined A$6,838 and ordered to apologise to the Parliament upon his return.

[21] He has since received a lot of criticism for this, not only for his decision to sign on the eve of the month-long caretaker period before the upcoming November 2014 state election and before two legal cases into the planning approval for the project were resolved, but also for his decision, at the insistence of the East West Connect consortium, to direct the then state treasurer Michael O'Brien to sign a "side letter" guaranteeing the consortium compensation of more than $1 billion in the event that the court cases were successful or if for some other reason the contracts were cancelled (which Labor promised to do if it won the election), which was thought to be a contributing factor in the state having to pay what is thought to amount to $1.1 billion to EWC upon the declaration by the then new Andrews government to suspend work in December 2014, and the contracts eventually being terminated in June 2015.

In December 2015, the Victorian Auditor General revealed the cost of both sections of the East West Link would have been close to $22.8 billion in nominal terms.

[23] Napthine stated that he intended to serve a full parliamentary term despite losing the Premiership,[24] however on 31 August 2015 he announced his resignation from the Victorian Parliament, which triggered a by-election in his electorate of South-West Coast.