Alexander McEachian Gallacher (1 January 1954 – 29 August 2021) was an Australian politician who was a Senator for South Australia from 2011 until his death in 2021.

[3] He was a member of the Australian Labor Party (ALP) and was a senior official in the Transport Workers Union of Australia (TWU) before entering parliament.

Within the union's South Australia/Northern Territory (SA/NT) branch, he held the positions of industrial officer (1988–1992), organiser (1992–1996), and state secretary (1996–2010).

Prior to the 2010 federal election, he won ALP preselection for the Senate in first position on the party's ticket in South Australia.

[4] Gallacher was diagnosed with lung cancer in January 2020 and took a leave of absence from the Senate to undergo treatment.