Centre Alliance (CA), formerly known as the Nick Xenophon Team (NXT), is a centrist Australian political party based in the state of South Australia. It currently has one elected representative, Rebekha Sharkie in the House of Representatives; since 2022 she has been the party's only candidate, describing herself as "a party of one", and citing savings in the party account as the main reason for her not to run as an independent.

Since its founding in July 2013, the party has twice changed names. At the time of the 2016 federal election, it was known as the Nick Xenophon Team. After Nick Xenophon founded SA Best, an affiliated state-based party, NXT sought to change its name to SA-BEST (Federal). However, prior to Australian Electoral Commission approval, Xenophon left politics, and the party withdrew its application and changed its name to Centre Alliance. In 2018, Centre Alliance senator Stirling Griff stated that SA Best is "a separate entity, a separate association, a separate party" from Centre Alliance.

The party's ideological focus is a combination of culturally liberal and populist policies, drawing from the positions of Xenophon. Its present members have variously declared support for same-sex marriage, reform of the Australian Intelligence Community, action on climate change, support for military veterans, affordable tax cuts, Australian-made manufacturing (including defence-industry spending), and legalising euthanasia.

Nick Xenophon ran for election as an independent candidate in Australia under a "No Pokies" ticket that ran in South Australian state elections from 1997 to 2006. He was elected in 1997 and 2006. The 2013 Australian federal election saw independent "Nick Xenophon Group", with Xenophon as the lead candidate, win 24.9 percent of the statewide upper house vote in South Australia. This was an unprecedented result for a non-major party with Nick Xenophon Group outpolling the Australian Labor Party to come in second behind the Liberal Party of Australia, which won office. Although Xenophon was re-elected, his running mate Stirling Griff narrowly missed out to Bob Day of the Family First Party.

In 2014, Nick Xenophon Team (NXT) emerged from Nick Xenophon Group. Its management committee was composed of Xenophon, John Darley, Griff, and Connie Bonaros.

In the 2014 South Australian state election, John Darley, who took Nick Xenophon's place in the state parliament in 2007, ran under the banner of Independent Nick Xenophon Team. Without Xenophon as a candidate, being in the national senate, John Darley won 12.9 percent of the statewide upper house vote. John Darley, who was appointed in 2007 to succeed Xenophon for "No Pokies", was re-elected.

On 5 March 2017, Xenophon announced that he would launch a new party in South Australia in time for the March 2018 state election to enable them to focus on domestic South Australian issues as opposed to wider Australia. The party was registered on 4 July as Nick Xenophon's SA-BEST.

The independent John Darley left the management committee of the Nick Xenophon Team party on 17 August 2017 to avoid expulsion from the party. He said: "There are many things I could say as to why I have resigned. However, it is not my place to speak publicly about internal party matters". Though it was stated that there had been months of conflict between Darley and the party, it came to a head a week prior when Darley voted with the Labor government to back Legislative Council voting reforms. Xenophon indicated the resignation had averted Darley's imminent expulsion from the party due to "breaches to party rules". Nick Xenophon's SA-BEST therefore contested the 2018 election without state parliamentary representation.