The Northrop Alpha is an American single-engine, all-metal, seven-seat, low-wing monoplane fast mail/passenger transport aircraft used in the 1930s.

In addition, the Alpha was the first commercial aircraft to use rubber deicer boots on wing and empennage leading edges which, in conjunction with state-of-the-art radio navigation equipment, gave it day or night, all-weather capability.

The Alpha entered service with Transcontinental & Western Air (TWA) making its inaugural flight on April 20, 1931.

TWA operated 14 aircraft until 1935, flying routes with stops in San Francisco, California; Winslow, Arizona; Albuquerque, New Mexico; Amarillo, Texas; Wichita, Kansas; Kansas City, Missouri; St. Louis, Missouri; Terre Haute, Indiana; Indianapolis, Indiana; Columbus, Ohio; Pittsburgh, Pennsylvania; Philadelphia, Pennsylvania; and New York.

[2] TWA's were initially operated as a passenger service but the Alpha's were later modified at the Stearman factory in Wichita into the cargo-carrying 4A model with a new type certificate.