A by-election was held in the State Electoral District of Marrickville in New South Wales, Australia on 17 September 2005. The by-election was prompted by the resignation of the sitting member Deputy Premier Andrew Refshauge (Labor) on 10 August 2005, in the wake of the resignation of Premier Bob Carr. The by-election was timed to coincide with two other state by-elections in Macquarie Fields and Maroubra.