Donald Gray Triplett was an American banker known for being the first person diagnosed with autism. He was first diagnosed by Leo Kanner in 1943, and was labeled as "Case 1". Triplett was noted for his savant abilities, particularly the ability to name musical notes played on a piano and the ability to perform rapid mental multiplication.

Leo Kanner was an Austrian-American psychiatrist, physician, and social activist best known for his work related to infantile autism. Before working at the Henry Phipps Psychiatric Clinic at the Johns Hopkins Hospital, Kanner practiced as a physician in Germany and South Dakota. In 1943, Kanner published his landmark paper Autistic Disturbances of Affective Contact, describing 11 children who displayed "a powerful desire for aloneness" and "an obsessive insistence on persistent sameness." He named their condition "early infantile autism". Kanner was in charge of developing the first child psychiatry clinic in the United States and later served as the Chief of Child Psychiatry at the Johns Hopkins Hospital. He is one of the co-founders of The Children's Guild, a nonprofit organization serving children, families and child-serving organizations throughout Maryland and Washington, D.C., and dedicated to "Transforming how America Cares for and Educates its Children and Youth." He is widely considered one of the most influential American psychiatrists of the 20th century.