Her career in B movies lasted a little more than decade, but the former model appeared in nearly 40 movies. She starred opposite Roy Rogers in Sheriff of Tombstone (1941), was the love interest of fictional boxer Joe Palooka in five low-budget films for Monogram Pictures, and played a nurse in the Abbott & Costello ski resort comedy Hit the Ice (1943).
After making the 1949 musical There's a Girl in My Heart, Knox quit the movies to raise her children with her husband, University of Michigan star and 1940 Heisman Trophy winner Tom Harmon.
She married Harmon in a wedding dress fashioned from the silk parachute that saved his life when he was shot down over China during World War II. Harmon, who went on to a career in sportscasting, died in 1990 at age 70.
In addition to Mark Harmon, survivors include daughter Kristin Harmon, who also went into acting and married teen idol Ricky Nelson; another actress daughter, Kelly Harmon; nine grandchildren, including actress Tracy Nelson and singer-songwriter twins Matthew and Gunnar Nelson (who perform as pop act Nelson); and two great-grandchildren.

source: yahoo