Trentbarton (stylised in all lowercase) is a bus operator providing both local and regional services in Derbyshire, Leicestershire, Nottinghamshire and Staffordshire, England. It is a subsidiary of the Wellglade Group.

In October 1913, the Trent Motor Traction Company was founded, commencing operations with a bus service between Ashbourne and Derby. A second service between Derby and Stapleford was introduced the following month. The Trent Motor Traction Company's buses were originally painted green; however, from 1923, the fleet colour was changed to red.

By 1925, a large network of services was operating from Derby, Loughborough and Nottingham; as services expanded, the Trent Motor Traction business grew, with a total of seven depots being established, with a total of 52 smaller operators subsequently acquired during the 1930s. Around this time, Trent Motor Traction standardised on buses manufactured by Midland Red, the last of which were delivered following the outbreak of the Second World War in 1940.

In August 1949, a co-ordination agreement was reached between the Trent Motor Traction Company and the Derby Corporation. A joint service operated by both Trent and Derby, running from the town to Cavendish via Corporation Avenue, was established, with return tickets purchasable for use on both operators' buses. This co-ordination scheme was maintained until the mid-1980s, being renewed in 1979 to split Derby's services to be operated 83.34% by Derby Transport, with the remaining 16.66% operated by Trent Motor Traction. Additionally in 1958, following the opening of the A52 road, Trent Motor Traction and neighbouring Barton Transport commenced operations of a joint express coach service between Derby and Nottingham.

In 1969, Trent Motor Traction, which had previously been under the ownership of British Electric Traction, became part of the National Bus Company (NBC), and in 1972, took over the operations of fellow NBC subsidiary Midland General, including its Notts & Derby Traction subsidiary; the identities of both companies, however, were retained as part of this takeover. A fire at the company's Meadow Road depot in Derby on the night of 14 July 1976 destroyed 40 buses and damaged another 12, and despite costing the operator £1 million (equivalent to £13,163,000 in 2023) in damages, operations ran as normal the following morning.

Following the passage of the Transport Act 1985, which deregulated the British bus industry and ordered the break-up of the National Bus Company, Trent Motor Traction was sold by the NBC in a management buyout, led by Brian King and Ian Morgan, to the Wellglade Limited holding company in January 1987, with the newly-independent business renamed Trent Buses. Trent Buses gained a 6% shareholding in Leicester City Transport in January 1988 following the sale of its competitive operations and depot in Loughborough, Leicestershire, and in 1989, the business of Barton Transport was purchased by Trent Buses for £22 million (equivalent to £69,134,000 in 2023), becoming a separate subsidiary company of the main Trent Buses operation, although both subsidiaries soon began co-ordinating their operations on a day-to-day basis. Following the introduction of a corporate livery scheme, the separate Trent Buses and Barton Transport companies began to be brought together as 'Trentbarton' from 2002 onwards, with a merger of the companies formally completed in 2005.

During September 2022, it was announced that managing director Jeff Counsell was to retire in February 2023. He was succeeded by Tom Morgan, the former commercial director for the Trentbarton and Kinchbus companies.

Trentbarton operates services from Loughborough, Ashbourne, Burton upon Trent, Chesterfield, Derby, Ilkeston, Mansfield, and Nottingham with most operating under a brand name with branded vehicles although some still use conventional route numbers, Some services within the network operate through to around 03:00 on Saturday and Sunday mornings.^{[citation needed]}