William Goldman is often credited as the first screenwriter to sell a spec script, meaning he wrote a script without getting paid for it then sold it once he was done with it. It’s common in the novel-writing world, but in the late 60s, it was unheard of in the film business. That script was “The Sundance Kid & Butch Cassidy,” which legendary producer Richard D. Zanuck, who was running 20th Century Fox at the time, optioned for twice what they were allowed to, knowing it was going to be big. And he was right. We continue our Couples On the Run series with George Roy Hill’s 1969 western, “Butch Cassidy & the Sundance Kid.”