I have chosen not to name the screenwriters because, in spite of what you might think, I am a merciful man.
A disclaimer: I have not fact-checked a single one of these lines. For the sake of the historical record, feel free to send corrections.
First prize of The Making of Alexander goes to Arthur Tiersky for this jaw-dropping monologue from the stinko John Belushi biopic, Wired:
John, there's a light within you. I want you to burn it out. BURN IT OUT! BURN IT OUT! In Vietnam, monks set themselves on fire. Artaud. Artaud said that actors should perform like they are on fire. Signaling through the flames ... THAT'S our job as comedians! To burn brightly and stand as a symbol. I will not give in to this consensus reality! Cut the demons loose, John! Let 'em loose! That's were your characters come from.
Second prize was not as easy to determine. It goes to Bret Thompson, and it's Lee Krasner's assessment of the painter's latest canvas in Pollack:
"You've done it this time, Pollack. You've broken it wide open."
A close runner-up (via Dan J. Vice, also cited in my Slate review) was the tribute of agent George Shapiro to his client, Andy Kaufman, in Man in the Moon: "You're insane—but you might also be brilliant." Also consider this, via Kevin Dafler, from the Richie Valens biopic La Bamba: "I'm going to be a star, and stars don't fall from the sky, do they?"
Category 2 offered some doozies, the chercest from Nicholas and Alexandra, via Paul Notley:
TROTSKY: You've been avoiding me, Lenin.
From the same movie, James Hynes remembers a Lenin line that went something like: "Nice work on the manifesto, Trotsky." A potential winner if the quotation had been exact!
Another good Category 2 exchange is this from The Greatest Story Ever Told, via Paul Hynes: