The Southerner was a passenger express train in New Zealand's South Island between Christchurch and Invercargill along the South Island Main Trunk, that ran from 1970 to 2002. It was one of the premier passenger trains in New Zealand and its existence made Invercargill the southernmost passenger station in the world.

The Main North Line between Picton and Christchurch and the Main South Line between Lyttelton and Invercargill, running down the east coast of the South Island of New Zealand, are sometimes together referred to collectively as the South Island Main Trunk Railway (SIMT). Construction of a line running the length of the east coast began in the 1860s and was completed all the way from Picton to Invercargill in 1945; the last sections being on the Main North Line south of Picton. The designation "South Island Main Trunk" originally referred to only that line between Christchurch and Invercargill.