The K sets are a class of electric multiple units (EMU) that currently operate on the Sydney Trains suburban network. Built by A Goninan & Co, the K sets first entered service in 1981 operating under the State Rail Authority, and later CityRail. The carriages are of stainless steel, double deck construction and share much of their design with the older S sets. 35 of the 40 K sets originally built remain in service as of July 2025. The K sets are currently the second oldest in the Sydney Trains fleet, and the oldest in the Suburban fleet.