Jane Seymour was 0 in Never Wave at a WAC when she played the character 'Lt. Col. Hubbard (uncredited)'.
That was over 71 years ago in 1953.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 72, and has starred in 107 movies in total, 106 of those since Never Wave at a WAC was released.
In Never Wave at a WAC, I think Jane Seymour looks: