Lewis Hyde Brereton (June 21, 1890 – July 20, 1967) was a military aviation pioneer and lieutenant general in the United States Air Force. A 1911 graduate of the United States Naval Academy, he began his military career as a United States Army officer in the United States Army Coast Artillery Corps prior to World War I, then spent the remainder of his service as a career aviator.

Brereton was one of the few senior U.S. commanders in World War II who served in combat theaters continuously from the Japanese attack on Pearl Harbor to the German surrender, and he saw action in more theaters than any other senior officer. He began World War II as a major general commanding the Far East Air Force in the Philippines and concluded it as a lieutenant general in command of the First Allied Airborne Army in Germany. Brereton commanded forces in four controversial events of the war: the destruction on the ground of much of the United States Army Air Forces in the Philippines, Operation Tidal Wave; Operation Cobra; and Operation Market Garden.

Brereton was one of the first military pilots of the United States Army, assigned to the Aeronautical Division, U.S. Signal Corps in September 1912. He was also one of five officers (the others being General of the Air Force Henry H. Arnold, Major Generals Frank P. Lahm and Benjamin D. Foulois, and Brigadier General Thomas DeW. Milling) who were members of the United States Air Force and all of its progenitors, but the only one to do so on continuous active duty (Arnold, Lahm, Foulois, and Milling were all on the retired list when the USAF came into being).

Brereton was born in Pittsburgh, in 1890, the second son of William Denny Brereton and Helen (Hyde) Brereton. The family moved to Annapolis, Maryland while Brereton's older brother, William Jr., was a midshipman at the Naval Academy. His father was a successful mining engineer and a 4th-generation Irish-American. His mother was English and Episcopalian by birth. At the age of eight, Brereton suffered a recurring infection of the middle ear, purulent otitis media, which proved impossible to treat in the pre-antibiotics era.

His personality characteristics were said to be "cool and thoughtful", able to "think rapidly on his feet", with a "quick, analytical mind". However, he was also said to have an "appropriate temper" and "able to swear in three or four languages", a "party-loving streak", and when referring to himself, to use the third person. He had a reputation, especially among critics, for being hedonistic. Gen. Omar N. Bradley, who intensely disliked Brereton, was quoted by a biographer of Dwight D. Eisenhower as saying that Brereton was "marginally competent ... (and) more interested in living in the biggest French chateau". However, from July 1942 to the end of the war, Brereton had a close association with and was well-regarded by Royal Air Force Air Marshal Sir Arthur Coningham, who found in him not just a fellow bon vivant but an effective air commander on whom he could rely for efficient and competent cooperation.

He attended St. John's College in Annapolis with the intention of entering West Point, but unable to secure an appointment, he followed his older brother into the Naval Academy in 1907, graduating in June 1911, ranked 58th in merit in a class of 194. In March 1911, he submitted a letter of resignation effective on the date of graduation, listing seasickness as a primary reason, and as a result, the Academy's Permanent Medical Examining Board rejected him for active duty. After two days as an ensign, his resignation was accepted. He applied for commissioning in the United States Army and was appointed a second lieutenant in the Coast Artillery Corps on August 17, 1911, and went on active duty September 6 with the 118th Company CAC at Fort Monroe, Virginia. The next year he served in the 17th Company CAC at Fort Washington, Maryland.

In September 1912, he volunteered for detached service with the Signal Corps' Aeronautical Division to undertake flying training at the planned aviation school at Rockwell Field, San Diego, California. He became the 26th serving officer so detailed. The lack of facilities at Rockwell forced most of his training to take place at the Curtiss Aeroplane Company in Hammondsport, New York during October 1912. Brereton returned to Rockwell in November, and after the Signal Corps Aviation School officially opened in December, passed the test qualifying him for a rating of Military Aviator on March 27, 1913, the 10th pilot to earn the rating. He began to train and instruct on float planes but experienced two crashes, the first as pilot of a fatal crash of a Curtiss F on April 8, 1913, and the second as an observer on May 21. At his own request, Brereton was relieved of aviation duties on July 3, 1913. He returned to the Coast Artillery Corps, posted to the 115th Company at Fort Rosecrans, on the Point Loma peninsula across the channel from Rockwell. While stationed in San Diego, he married Helen Clason Willis on February 27, 1913, and subsequently had two children.

In July 1916, he was promoted to first lieutenant and sent to the Philippines to join the 1st Company, Fort Mills (138th Company CAC) on Corregidor. Less than two months later he requested to return to the Aviation Section, Signal Corps. Because of the "Manchu Law" regulating length of detached service away from an officer's permanent branch, Brereton first transferred to the 17th Field Artillery Regiment to qualify, and was assigned to duty with the 2nd Aero Squadron, also stationed on Corregidor, on January 17, 1917. Returning to the United States in March 1917, he was assigned to duty in Washington, D.C., at the Aviation Section headquarters in the Office of the Chief Signal Officer.