A bus conductor (also referred to as a conductor or clippie) is a person (other than the driver) responsible for collecting fares from bus passengers. Bus conductors were a common feature of many bus services across Europe until the late 1970s and early 1980s. The main reason two-person crews were needed was that most towns and cities used double-decker buses for urban services. Until the 1960s, all double deck vehicles were built with front-mounted engines and a "half-cab" design, such as the familiar AEC Routemaster London bus. This layout totally separated the driver from the passenger saloons. The conductor communicated with the driver using a series of bell codes, such as two bells to start (the well-known "ding-ding").

Many half-cab double-deckers were boarded from an open platform at the rear, while others were equipped with a forward entrance and staircase and driver-operated doors. Each case required a conductor to collect fares and, especially on the rear-entrance design, supervise passenger loading and unloading. Some bus services in the late 1960s and early 1970s experimented with later-model forward entrance half-cab double-deckers—removing the conductor and having the driver sell tickets, as on the rear entrance buses that were common by that time. The hope was to have the benefits of one-person operation without the cost of replacing vehicles that still remaining service life. This idea was soon scrapped and the buses reverted to conventional conductor operation.