Charmian Carr, who played Liesl von Trapp in 'The Sound of Music', has died at the age of 73.
The actress' spokesman said she died in Los Angeles on Saturday of complications from a rare form of dementia.
Carr was a college student when she auditioned for the 1965 film, which also starred Julie Andrews and Christopher Plummer.
She performed the song 'Sixteen Going On Seventeen' in the Rodgers and Hammerstein film.
Carr later wrote a pair of books about her experiences, Forever Liesl and Letters To Liesl.
The actress also starred in the Stephen Sondheim television musical 'Evening Primrose' with Anthony Perkins.
Kym Karath, who played Gretl, the youngest of the von Trapp children, wrote on Twitter: "It is with infinite sadness that I share the tragic news that the precious & exquisite Charmian Carr, beautiful Liesl, has passed away."
It is with infinite sadness that I share the tragic news that the precious & exquisite Charmian Carr , beautiful Liesl , has passed away .
— Kym Karath (@KymKarath) 18 September 2016
Actor Nicholas Hammond, who played Friedrich, also paid a touching tribute:
May she rest in peace. And forever dance around the gazebo. pic.twitter.com/9nOU4cY104
— Nicholas Hammond (@nicholasham1) 18 September 2016
This is in reference to one of her most famous scenes in the film, which saw Carr's character perform her signature song.
In a statement, Ted Chaplin from Rodgers & Hammerstein said: "It's always sad when a member of the family passes away - and in the case of the 'family' of the movie The Sound Of Music, it's especially sad when it is the first of the group to go.
"Charmian Carr played the oldest Von Trapp child, and in some ways she maintained that role in real life - guiding, cheering, supporting and generally being there for the rest of her 'sisters' and 'brothers'.
"She was a great ambassador, and we had so many good times together, either working on Sound Of Music related events, or, something I will always remember, arranging for her to be a special guest at New York's Symphony Space's 'Wall to Wall Stephen Sondheim', reminding that audience that Charmy did, in fact, star opposite Anthony Perkins in the 1967 TV musical Evening Primrose.
"I will miss her, well, charm and her spirit. We all send condolences to her family."
Twentieth Century Fox said on Twitter: "The Sound of Music lost a beloved member of the family w/ the passing of Charmian Carr. She will be forever missed."
The Sound of Music lost a beloved member of the family w/ the passing of Charmian Carr. She will be forever missed. pic.twitter.com/ehqec4uWrr
— 20th Century Fox (@20thcenturyfox) September 18, 2016
And actor and director Seth MacFarlane wrote: "So very saddened to hear of the death of Charmian Carr. She leaves behind one of the most memorable performances in movie history."
