Howard Hughes also designed the P-38. ....I."
Hughes tried to sell two types of twin engine, twin boom aircraft to the Army Air Corps during WW2, but the P-38 was chosen over both, one of which had only a prototype built and the second didn't have a prototype flying until 1946. The P-38 was retired by then.
AFAIK, the P-38 was Kelly Johnson's baby, who also was one of the Lockheed engineers on the Constellation design team.
Howard Hughes pushed the Constellation concept to Lockheed, who were skeptical, after he took stock control of TWA. Hughes took on the financial risks, but AFAIK, he was not ever a designer/engineer for Lockheed.
From the P-38, Kelly Johnson pushed on to design the F-104, U-2, several supersonic and hypersonic drones, the A-12 and SR-71. He was one of the most remarkable aircraft engineers and team leaders in aviation history.