Frederick Sumner Brackett (August 1, 1896 – January 28, 1988), was an American physicist and spectroscopist.
Born in Claremont, California, to Frank and Lucretia Brackett, he graduated from Pomona College and worked as an observer at Mount Wilson Observatory until 1920.
He moved to the Washington area and joined the Department of Agriculture's Fixed Nitrogen Lab in 1927.
At NIH, he was a scientist in the Division of Industrial Hygiene, where he developed spectrometers to detect toxic substances in body fluids, including one containing two of the largest natural quartz prisms in the world.
He was promoted to the rank of lieutenant colonel and received the Legion of Merit for his work.