Jean Piaget: A renowned stage theorist known for his theory of cognitive development. He proposed that children progress through four stages of cognitive development: sensorimotor, preoperational, concrete operational, and formal operational.
Erik Erikson: Another influential stage theorist who focused on psychosocial development. He suggested that individuals go through eight stages throughout their lifespan, each involving a specific developmental task or crisis to resolve.
Lawrence Kohlberg: A stage theorist who developed a theory of moral development. According to Kohlberg's theory, individuals progress through six stages of moral reasoning as they mature morally.