The Alexander ALX400 (later known as the TransBus ALX400 and the Alexander Dennis ALX400) was a 2-axle double-decker bus body built by Walter Alexander Coachbuilders (later by TransBus International/Alexander Dennis). It was one of the ALX-series bodywork, all of which (except the ALX100) featured the same designs on the front and rear panels that were originally designed for the new generation of mainly low-floor bus chassis produced since the late 1990s.