When the studio began shopping around Trek to the networks, CBS was the first to show interest. After a 2 hour pitch meeting, Roddenberry was furious to hear "Thank you, we have one of our own that we like better."
What series, which ran from 1965-68, and featured a couple of slightly different themes by an unknown composer named Johnny Williams, was the "one of our own" science fiction show that was being referred to by CBS executives?
Lost in Space