Ken Keyes, Jr. was an American personal growth author and lecturer whose 1981 book The Hundredth Monkey served as the source material for the 1986 anime film 100 Banme no Saru (also known as Hyakubanme no Saru or The Hundredth Monkey). Born in Atlanta on January 19, 1921, Keyes attended Duke University and the University of Miami, where he earned a degree in psychology. He contracted polio at age 25, which resulted in quadriplegia, and he used a wheelchair for the remainder of his life. During the 1970s, he founded the Living Love Center in Berkeley and developed a self-help system known as the Living Love method, authoring fifteen books on personal growth and social consciousness that collectively sold approximately four million copies.

The anime 100 Banme no Saru is a short film released on May 25, 1986, produced by Kyowa Film. It adapts Keyes book, which popularized the hundredth monkey effect—an apocryphal story about Japanese macaques on the island of Kojima. The book and film use this narrative as a parable for the antinuclear movement, suggesting that once a critical number of people adopt a new idea or behavior, it can spread spontaneously across a population. The anime runs approximately 15 to 20 minutes and carries a G rating, intended for all ages.

Keyes is not known to have created any other original anime or manga works beyond this single adaptation. His primary career was as a writer and speaker in the human potential and New Age movements, with books including Handbook to Higher Consciousness and How to Make Your Life Work. He died of kidney failure in Coos Bay, Oregon, on December 20, 1995.