Frederic G. Melcher
Melcher proposed the Caldecott Medal in 1937 to honor children's picture books. Named for British illustrator Randolph Caldecott, the medal is presented annually for the "most distinguished picture book for children".
Kate Greenaway Medal
Gail E. Haley was the first illustrator to win both medals, albeit for different works: the 1971 Caldecott for "A Story a Story" (1970) and the 1976 Greenaway for "The Post Office Cat". She also wrote both books.