Kym Karath

Anthea Kym Kym Karath is an American actress, best known for her role as Gretl, the youngest of the Von Trapp children, in The Sound of Music.

Although Karath was born in Los Angeles, United States, her family was actually Greek. Her original surname was Karathanasis, but then it was changed to Karath by her father. She has an older sister, Francie, who auditioned for the eldest Von Trapp child in The Sound of Music, a role that eventually went to Charmian Carr.

Source: Wikipedia