The Knight Bus is a triple-decker purple AEC Regent III RT bus from the book and film Harry Potter and the Prisoner of Azkaban later in Harry Potter and the Order of the Phoenix. It is heavily enchanted and has the abillity to squeeze itself very thin to go beteen two cars. It is also capable of very high speed travel, faster than a broomstick, and is invisible to Muggles. For long distances the bus can leap 100 miles. For a small additional fee, passengers can have hot water bottles, toothbrushes and hot chocolates.
The bus serves as a convenient means of transport for witches and wizards within Britain.
The conductor is Stan Shunpike and the driver is Ernie Prang.