Matthew Morris Aid (March 11, 1958 – August 20, 2018) was an American military historian and author. Aid graduated from Beloit College in 1980, having studied international relations. He studied the Russian language, while a member of the United States Air Force, and was a Russian linguist for the National Security Agency, and the Air Force.

During his career, he became an expert on signal intelligence and the history of the NSA. Aid has been interviewed by multiple organizations including National Public Radio and C-SPAN and his work has been published in numerous journals, newspapers, and magazines including Foreign Policy, Politico magazine, National Security Archive, and the Associated Press.

Matthew Morris Aid was born on March 11, 1958, in New York City. His father, Harry, was an attorney for Mobil Oil and his mother, Rita, was a political activist. His family lived in France and Libya, when he was a young boy, and he attended an American-run oil companies school, outside of Tripoli, Libya from 1963 to 1967.

In an opinion article Aid wrote, in 2011, he recalled his family's experience during the Six Day War, when they were forced to evacuate, to a nearby Air Force base, where they were taken to Spain. He wrote, "I remember vividly as our car was stoned by mobs of angry Libyan youths as my mother drove through downtown Tripoli on the way to the base."

After his family returned to the U.S., his brother, Jonathan, described how 12-year old Aid would tell their parents that he was going to the library, but would instead take the train to the National Archives. Aid attended high school in New York City, where his interest in collecting declassified documents and love of playing war games, led him to become friends with John Prados, a National Security Archive fellow, who was attending graduate school at Columbia University and at the time, designed board war games. Prados recalled his disappointment when Aid left for Beloit College, in Wisconsin, saying Aid would share documents with him and was, "one of my best playtesters." After graduating from Beloit, where he studied international relations and Russian, he enlisted in the Air Force, where he became a Russian language expert.

After leaving the military, Aid spent 20 years as a corporate investigator. However, Aid considered himself an independent scholar, who enjoyed studying documents from libraries and the National Archives in College Park, Maryland, saying "any spare time I have, I run up to the National Archives to do historical research."

In 2005, Aid, a visiting fellow at the National Security Archive, made his first contribution to the National Security Archive, while he did research for his book about the NSA's history. Examples of some of the discoveries made in his research include a Gulf of Tonkin incident that higher level officials had refused to declassify, and secret investigations into Martin Luther King, Muhammad Ali and Art Buchwald.

In 2006, his research led to the discovery that over 25 thousand records had been removed from the National Archives.