Janet Leigh was 19 in The Romance of Rosy Ridge when she played the character 'Lissy Anne MacBean'.
That was over 77 years ago in 1947.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
In 2004 she died aged 77, starring in 88 films in her career, 85 of those after The Romance of Rosy Ridge was first released. If she were alive today she would be 96.
In The Romance of Rosy Ridge, I think Janet Leigh looks: