The Noah is a 1975 post-apocalyptic film starring Robert Strauss (in his last film), Geoffrey Holder, and Sally Kirkland. It's the story of the last survivor on Earth and how he copes -or fails to cope.
DVD Talk says, "The Noah is about as obscure as apocalyptic science fiction films get" and concludes, "there's enough there that more adventurous viewers will want to see it once. It's a sincerely-made, ambitious effort, and parts of it are evocative and effective." DVD Beaver describes it as "a disturbing journey into genuine terror via the torment of a lost soul whose mind has hopelessly frayed" and "a harrowing psychological drama". Quiet Earth has an overview.