Seinfeld Episodes on Instagram: "Rob Reiner, the acclaimed director of films like When Harry Met Sally and This Is Spinal Tap, was instrumental in saving Seinfeld from early cancellation at NBC, as his production company, Castle Rock Entertainment, produced the show, championing it despite low initial ratings until it became a cultural phenomenon. He believed in the unique comedic vision of Jerry Seinfeld and Larry David, helping it survive its rocky start to become a legendary series. The Seinf