Stephen Gammell grew up in Iowa. His father, an art editor for a major magazine, brought home periodicals that gave Stephen early artistic inspiration. His parents also supplied him with lots of pencils, paper, and encouragement. As an artist, he is self-taught.
He started his career with freelance commercial work, but became interested in children's book illustration. His first picture book, A Nutty Business by Ida Chittum, was published in 1973 and featured a war between squirrels and a farmer. That same year he illustrated The Search, a juvenile biography of Leo Tolstoy by Sara Newton Carroll. He has since illustrated nearly sixty titles.
Gammell is particularly well known for the surreal, unsettling illustrations he provided for Scary Stories to Tell in the Dark, a series of horror short stories by Alvin Schwartz that is still an adolescent favorite.
He and his wife, Linda, a photographer, live in St. Paul, Minnesota. He works daily in his studio, located above a restaurant.