Harry Grindell Matthews (17 March 1880 – 11 September 1941) was an English inventor who claimed to have invented a death ray in the 1920s.

[2] In 1911, Matthews claimed that he had invented an Aerophone device, a radiotelephone, and transmitted messages between a ground station and an aeroplane from a distance of 2 miles (3.2 km).

In 1914, after the outbreak of the First World War, the British government announced an award of £25,000 to anyone who could create a weapon against zeppelins or remotely control uncrewed vehicles.

Matthews successfully demonstrated it with a remotely controlled boat to representatives of the Admiralty at Richmond Park's Penn Pond.

Matthews also claimed that with enough power, it could shoot down aeroplanes, explode gunpowder, stop ships, and incapacitate infantry from the distance of 4 miles (6.4 km).

Matthews did not reply to them but spoke to journalists and demonstrated the ray to a Star reporter by igniting gunpowder from a distance.

On 27 May 1924, the High Court in London granted an injunction to Matthew's investors that forbade him from selling the rights to the death ray.

Public furore attracted the interest of other would-be inventors who wanted to demonstrate death rays to the War Office.

On 28 May, Commander Kenworthy asked in the House of Commons what the government intended to do to stop Matthews from selling the ray to a foreign power.

The government required that Matthews use the ray to stop a petrol motorcycle engine in the conditions that would satisfy the Air Ministry.

Sir Samuel Instone and his brother Theodore offered Matthews a huge salary if he kept the ray in Britain and demonstrated that it actually worked.

The only demonstration Matthews was willing to give was to make a Pathé film The Death Ray to propagate his ideas to his satisfaction.

Matthews demonstrated it in Hampstead by projecting an angel, the message "Happy Christmas", and a reportedly "accurate" clock face.

In 1938, Matthews married Ganna Walska, a Polish-American opera singer, perfumer, and feminist, whose four previous husbands had owned fortunes totalling $125,000,000.

[9] In 1935, Matthews became involved with the right-wing Lucy, Lady Houston, and intended to conduct experiments in French naval submarine detection from her luxury yacht, the Liberty.