Ralph, who was best known for playing the ultimate father figure John Walton, passed away late on Thursday in Palm Desert, California.
Ralph starred throughout the nine seasons of 'The Waltons' from 1972 and the subsequent TV film sequels.
He went on to appear in episodes of 'NCIS', 'Days of Our Lives', 'Grey's Anatomy' and 'Bones'.
Michael Learned, who portrayed Ralph's on-screen wife in the series, told The Hollywood Reporter: "Ralph was a good honest actor and a good honest man.
"He was my spiritual husband. We loved each other for over forty years. He died a working actor at the top of his game. He was a loving mentor to many and a role model to an entire generation. I'm devastated."
Ralph is survived by his third wife Linda East and two daughters Kathleen and Suzanne.