死光（英语：Death Ray），亦作殺人光線（日語：さつじんこうせん）或死亡射線。在一種理論物理學上，利用粒子束或電磁波（包括光）為基礎的武器，其高峰研究期位於1920年代到1930年代。當中以尼古拉·特斯拉（Nikola Tesla）及Harry Grindell-Matthews最為知名，其他獨立研究者還有Edwin R. Scott及Graichen，他們都是死光武器研究的先驅。研究現時基本終止，但在科幻小說裡經常都有出現。1957年，美國的全國發明家理事會在其發表的所需的軍事發明列表內，當中仍然包括有死光。
- To, Wireless. Finds a 'Death Ray' Fatal to Humans. German Scientist Says it Inflames and Destroys Cells, Hence Aids in Disease. Expects to Split Atom. Dr. Graichen Has Device to Make Blind See With Light Sent Through the Skull.. New York Times. 1928-06-04 [2007-07-21].
Berlin, June 3, 1928. The discovery of a new 'death ray,' capable of destroying, though not intended to destroy, human life, has just been announced by Dr. Graichen, a young physicist and engineer employed as an experimenter by the Siemens Halske Electric Company.
- The 'Death Ray' Rivals. New York Times. 1924-05-29 [2007-07-21].
The inventors of a 'death ray' multiply every day. To H. Grindell-Matthews and Professor T.F. Wall have been added two other Englishmen, Prior and Raffe, and Grammachikoff, a Russian. Herr Wulle, 'chief of the militarists' in the Reichstag, has informed that body that the Government has a device that will bring down airplanes, stop tank engines, and 'spread a curtain of death.'
- Denies British Invented 'Death Ray'. E.R. Scott Asserts He and Other Americans Preceded Grindell-Matthews.. New York Times. September 5, 1924, Friday.
Washington, DC, September 4, 1924 Edwin R. Scott an inventor of San Francisco, today challenged the assertion of Mr. Grindell-Matthews, who sailed for London on the Homeric last week, that the latter was the first to develop a 'death-ray' that would destroy human life and bring down planes at a distance.
- Death Stroke. Time (magazine). August 10, 1925 [2007-07-21].
Utmost secrecy always shrouds the structural details of new munitions of war. This one, announced last week by its inventor, Dr. Edwin R. Scott, is called the 'death stroke' or 'canned lightning.' The Navy Department, which has been in touch with Dr. Scott's researches, hinted that the ultraviolet ray was involved, but Dr. Scott stated specifically: 'There is no ray or beam about it.'
- Defense Update article on M-THEL
- Microwave weapons: Wasted energy (Nature)
- High Power Microwaves - Strategic and Operational Implications for Warfare (Eileen M. Walling, Colonel, USAF)
- HAARP - High Frequency Active Auroral Research Program