The Supermarine Nighthawk or P.B.31E was a First World War British aircraft, designed by Noel Pemberton Billing and built at Woolston, Southampton after Pemberton Billing's company became Supermarine Aviation Works Ltd. The P.B.31E, as with its predecessor the P.B.29 "Battle Plane", was an anti-Zeppelin night fighter. It was operated by a crew of three to five, and was designed to fly for 9–18 hours. The prototype of the P.B.31E flew in February 1917. It quickly became obsolete when it was found that Zeppelins could be more easily be destroyed by igniting their hydrogen bags using explosive bullets. Only a prototype aircraft was built.

Noel Pemberton Billing, sometimes known as Noel Pemberton-Billing, was a British aviator, inventor, publisher and Member of Parliament for Hertford. He founded the firm that became Supermarine and promoted air power, and held a strong antipathy towards the Royal Aircraft Factory and its products. He was noted during the First World War for his populist views and for a sensational libel trial.