Frank B. Gilbreth Jr. was an American author and engineer, born in 1911. He is best known for co-authoring the book “Cheaper by the Dozen” with his sister, which recounts the experiences of their large family and their father’s innovative approaches to efficiency and time management. Gilbreth Jr. was the son of Frank B. Gilbreth Sr., a pioneer in the field of motion study and scientific management. His work and writings contributed to the understanding of family dynamics and the impact of his father's methods on everyday life.