401 (disambiguation)

401 may refer to:


 * 401 (number), the natural number following 400 and preceding 402
 * A year: 401 BC or AD 401
 * Ontario Highway 401, a highway that extends across Southern Ontario, Canada
 * There are also other roads named 401, see the List of highways numbered 401
 * 401(a), a type of U.S. tax-deferred retirement savings plan defined by a subsection of the Internal Revenue Code
 * 401(k), a type of U.S. employer-sponsored retirement plan defined by a subsection of the Internal Revenue Code
 * Bristol 401, a car produced by Bristol Cars in the early 1950s
 * HTTP 401, a status in the HTTP protocol indicating authentication has failed
 * .401 Winchester Self-Loading centerfire rifle cartridge introduced in 1910
 * Area code 401
 * Cessna 401, an airplane
 * Peugeot 401, a family car