1. Gretl von Trapp (Kym Karath): The youngest of the von Trapp children, Gretl is a lively and bubbly character who loves music and singing.
2. Kurt von Trapp (Duane Chase): The second youngest in the von Trapp family, Kurt is a mischievous and energetic boy with a passion for music.
3. Brigitta von Trapp (Angela Cartwright): The third oldest von Trapp child, Brigitta is known for her kindness and compassion. She becomes close friends with Maria and often aids her in her efforts to bring music back into the family's lives.
4. Marta von Trapp (Debbie Turner): The fourth oldest von Trapp child, Marta is characterized by her shy and gentle nature. She loves singing but often lacks the confidence to perform.
5. Louisa von Trapp (Heather Menzies): The fifth oldest von Trapp child, Louisa is a strong-willed and confident individual. She is particularly fond of singing and dreams of becoming a professional singer one day.
6. Friedrich von Trapp (Nicholas Hammond): The sixth oldest von Trapp child, Friedrich is a sensitive and introspective boy. He develops a close bond with Maria and often seeks her guidance and advice.
7. Liesl von Trapp (Charmian Carr): The eldest of the von Trapp children, Liesl is a graceful and poised teenager. She falls in love with Rolf Gruber, the son of the local postmaster, and faces opposition from her father who disapproves of their relationship.