“So you’re a private detective. I didn’t know they existed, except in books, or else they were greasy little men snooping around hotel corridors.” Leigh Brackett, Anita Loos, Frances Marion. In film history, these screenwriters aren’t mentioned with the frequency of Billy Wilder or Preston Sturges, but they wrote some of the most celebrated movie classics that made waves in Hollywood. “Now you’re afraid you’re going to take me in your arms.” Anita Loos was one of the most powerful screenwriters the first half of the 20th century, also writing plays and novels. Her credits include D.W. Griffith’s “Intolerance,” and George Cukor’s “The Women.” “You filthy — ” “Don’t start calling names, you Park Avenue playgirl. I know a lot more words than you do.” And her novel, “Gentlemen Prefer Blondes,” was adapted twice for the big screen. “You do wear it on your head. I just love finding new places to wear diamonds.” Leigh Brackett gave the lines of Humphrey Bogart and Lauren Bacall energy and character for “The Big Sleep.” “I see. No professional secrets.” “Nope.” “I thought you wanted a drink.” “I changed my mind.” “Then what — ” That was based on a Raymond Chandler novel, and she worked with William Faulkner to adapt it. But it was her ear for dialogue that shined through. “Looks like we’re closed for the rest of the afternoon.” In the early years of Hollywood, Frances Marion was one of the industry’s most prolific writers with more than 300 screenplays to her credit. She wrote tough guy dialogue like the kind in the 1930 prison drama “The Big House,” and she even visited San Quentin to research it. For her efforts, she won the first Oscar awarded to a female screenwriter. “First time in prison?” “Yes.” “Sir, to me.” “Yes, sir.”