2016 Australian Senate election

The 2016 Australian federal election in the Senate was part of a double dissolution election held on Saturday 2 July to elect all 226 members of the 45th Parliament of Australia, after an extended eight-week official campaign period. It was the first double dissolution election since the 1987 election and the first under a new voting system for the Senate that replaced group voting tickets with optional preferential voting.

The final outcome in the 76-seat Australian Senate took over four weeks to complete despite significant voting changes. Earlier in 2016, legislation changed the Senate voting system from a full-preference single transferable vote with group voting tickets to an optional-preferential single transferable vote. The final Senate result was announced on 4 August: Liberal/National Coalition 30 seats (−3), Labor 26 seats (+1), Greens 9 seats (−1), One Nation 4 seats (+4) and Nick Xenophon Team 3 seats (+2). Former broadcaster and founder of the Justice Party Derryn Hinch, won a seat, while Jacqui Lambie, Liberal Democrat David Leyonhjelm and Family First's Bob Day retained their seats. The number of crossbenchers increased by two to a record 20. The Liberal/National Coalition will require at least nine additional votes to reach a Senate majority, an increase of three.

A number of initially-elected senators were declared ineligible a result of the 2017–18 Australian parliamentary eligibility crisis, and replaced after recounts.