I'm thinking of the similarities between Jack Benny's "New Year Talent Shows", and "American Idol". Both feature a celebrity appearance (Nanette Fabray, George Jessel, Jayne Mansfield). Both feature class acts (Eddie Anderson, The Sportsmen Quartet). Both have moments which have to be seen to be believed (Mel Blanc as Mr. Spritzer, The Landrews Sisters, one broadcast even ends with contestants fighting over who won).
Of course "The Jack Benny Program" follows a script, and the contestants are actors. "American Idol" is not scripted, yet they do have many a "theme night", to sort of guide the youngsters with material. Still, the spirit between these two programs seems unusually close.
...Although... Jack would NEVER verbally abuse a contestant!