Brett John Mason (born 5 March 1962) is an Australian former politician and diplomat.

[1] Following Mason's entry into the Senate in 1999, he was appointed Parliamentary Secretary to the Minister for Health and Ageing in the Howard government from 21 March 2007 to 3 December 2007, and appointed Parliamentary Secretary to the Minister for Foreign Affairs in the Abbott government from 18 September 2013 to 23 December 2014.

[1][2] Along with senators Mitch Fifield and Mathias Cormann, Mason was one of the first to resign from the Coalition front bench in 2009 over the Shadow Cabinet's decision to support Kevin Rudd's ETS.

[3] On 24 March 2015, Mason announced he intended to resign from the Senate prior to the parliament's budget sittings in May.

[6] On 21 April 2015, six days after his resignation from the Senate, Foreign Minister Julie Bishop announced that Mason would be appointed as Australia's ambassador to the Netherlands, replacing Neil Mules in mid-2015.