- For 3-axle, longitudinal-engine Dennis Trident built for export, see Dennis Trident 3/Dennis Trident E500.
Dennis Trident 2 (marketed as Dennis Trident, but once known as TransBus Trident 2/TransBus Trident) is a 2-axle low-floor double-decker bus chassis originally built by Dennis in the United Kingdom, which was unveiled in 1997 and replaced the Dennis Arrow. It was built by TransBus after Dennis was incorporated into the group in 2001 (the Dennis brand name was once dropped). From 2004, it was built by Alexander Dennis.
The Trident 2 chassis features a transversely mounted engine on the right side, with the radiator mounted on the left side of the engine compartment. It could be fitted with Cummins C-series Euro II engine (later Cummins ISCe Euro III engine), coupled to Voith DIWA or ZF Ecomat gearbox. Trident 2 was available with Alexander ALX400, Plaxton President and East Lancs Lolyne/Myllennium Lolyne bodywork.
In the first few years of production, Trident 2 was popular in the United Kingdom, with a large number sold to large bus operators such as Stagecoach, First Group, Travel West Midlands and Lothian Buses. Some of the Tridents were exported to Ireland (for Dublin Bus ) and Spain (for sightseeing operations in Barcelona and Madrid). But later, due to increased competition after the launch of Scania OmniDekka and TransBus being put into administration, the sales of Trident 2 dropped significantly, leaving Stagecoach as its major buyer.
In 2005, Alexander Dennis developed the new version of Trident 2 chassis for its Enviro400 double-decker. Marketed as the Enviro400 chassis, the name "Trident 2" continued to appear on the manufacturer's plate  and it retained the Cummins ISCe Euro III engine (soon replaced by Cummins ISBe 6-cylinder Euro IV) and Voith/ZF gearbox, it also received a number of modifications such as a longer front overhang, with a different shape of fuel tank became available. Production of the older version of Trident 2 chassis continued until 2006, with the newest example being delivered to Isle of Man Transport.
In 2008, Alexander Dennis unveiled the hybrid-electric powered version of Trident 2 (the Enviro400H) using BAE Systems's HybriDrive series drive system with Cummins ISBe 4-cylinder engine fitted for power generation.  Also in the same year, Alexander Dennis unveiled the further developed version of Trident 2 for the "New Generation" Enviro400, with the engine being moved to the left side and the radiator being moved to the right side of the engine compartment.  It could be fitted with Cummins ISBe Euro V or MAN D0836 engine, coupled to Voith DIWA or ZF EcoLife gearbox. In 2009, Alexander Dennis developed the Hong Kong version of the Trident 2 (Enviro400). Based on the further developed version unveiled in 2008, it has a longer rear overhang and could be fitted with Cummins ISLe Euro V engine.
- Product description in Alexander Dennis official website
- Product description of Enviro400 hybrid from BAE Systems