Metrobus is a high frequency, high capacity bus network in Sydney, Australia, first introduced in 2008. Metrobus services run every 10 minutes during peak periods, 15 minutes during off-peak weekday periods, and 20 minutes on weekends, linking key commercial suburbs and centres throughout the city, with the intention of making timetables obsolete. All buses were initially painted in a distinctive red livery but recently, the standard Transport for NSW livery of blue and white has been adopted. All Metrobus services are wheelchair accessible. All route numbers were prefixed with an "M" followed by a two-digit number.

The State Transit Authority of New South Wales, also referred to as State Transit, was an agency of the Government of New South Wales operating bus services in Sydney. Superseding the Urban Transit Authority in 1989, it was also responsible for the provision of ferry services in Sydney until 2004 and bus and ferry services in Newcastle until 2017. It ceased trading after 2 April 2022 with its remaining operations to be contracted out by Transport for NSW to replacement operators.