The Northrop Corporation was a leading aircraft manufacturer of the United States.

The Northrop P-61 Black Widow night fighter first flew in 1942 and remained in operational use until the early 1950s

Jack Northrop founded three companies using his name. The first was the Avion Corporation in 1927, which was absorbed in 1929 by the United Aircraft and Transport Corporation as a subsidiary named "Northrop Aviation Corporation". The parent company moved its operations to Kansas in 1931, and so Jack, along with Donald Douglas (of Douglas Aircraft Company fame), established a "Northrop Corporation" located in El Segundo, California, which produced several successful designs, including the Northrop Gamma and Northrop Delta. However, labor difficulties led to the dissolution of the corporation by Douglas in 1937, and the plant became the El Segundo Division of Douglas Aircraft.

Northrop still wanted his own company, and so in 1939 established the "Northrop Corporation" that lasted until 1994.

In 1994 the company merged with Grumman to form Northrop Grumman.

The company was notable in the 1940s for experimentation with flying wings; although a number of designs were flight-tested, only the B-2 stealth bomber of the 1980s ever made it to production and deployment.

Northrop Aircraft Corporation:

• Northrop Alpha
• Northrop Beta

Northrop Corporation (I), later El Segundo division of Douglas:

• Northrop Gamma
• A-17
• BT-1 - later TBD Dauntless
• Northrop Delta

Northrop Corporation (II):

• N-3PB
• P-61 Black Widow
• YB-35
• XP-56
• XP-79 Flying Ram
• YB-49
• N-32 Raider
• F-89 Scorpion
• X-4 Bantam
• F-5 Freedom Fighter
• T-38 Talon
• YA-9A
• YF-17 Cobra
• F-20 Tigershark
• HL-10
• Tacit Blue
• B-2 Spirit
• YF-23 Black Widow II (with McDonnell Douglas)