One of the most instantly quotable and beloved films of all time, "The Princess Bride" was released in 1987, and has proven itself a timeless classic. Written by William Goldman (based on his 1973 novel) and directed by Rob Reiner, the film is a twist on typical fairy tales that has it all: swashbuckling, comedy, revenge, and of course, swoon-worthy romance — don't worry, it's not a kissing book. Framed by a grandfather (Peter Falk) reading the novel to his grandson (Fred Savage), "The Princess Bride" centers on the love story between Buttercup (Robin Wright) and her farmhand Westley (Cary Elwes). The two are separated and there are quite a few obstacles for them to overcome in order to be reunited, including a wicked prince (Chris Sarandon) with designs on Buttercup, Rodents of Unusual Size and … death. Thankfully, "death cannot stop true love."

One of the film's greatest strengths is its cast of unforgettable characters, such as swordsman-seeking-vengeance Inigo Montoya (Mandy Patinkin) and his towering but lovable companion Fezzik (André the Giant), who join Westley on his quest after he defeats their employer Vizzini (Wallace Shawn) — "inconceivable!" There are other heroes and villains they meet along the way, and though Goldman's script is undeniably excellent, not all the actors adhered to the words he had written. In fact, one barely seemed to pay attention to them all.

So, which actor improvised the majority of their performance?

It Would Take A Miracle

Despite being onscreen for about five minutes, Billy Crystal's role as Miracle Max, the miracle worker who saves Westley from being "all dead," leaves an indelible mark on "The Princess Bride." Interestingly, the actor's performance was almost entirely improvised. Even before the film began shooting, Crystal was helping to shape Max. According to the film's 2001 documentary "As You Wish: The Story of The Princess Bride" (via Atlas Obscura), director Rob Reiner paired the actor with Peter Montagna, a makeup artist Crystal had previous experience with on "Saturday Night Live." From the beginning, the actor brought reference photos of both his grandmother and early 20th century baseball manager Casey Stengel. It was from this combination of images that Miracle Max's look was born.

Cary Elwes described what happened next in his book "As You Wish: Inconceivable Tales From the Making of The Princess Bride." The actor said that from the moment Max pokes his head through that wooden peephole, Crystal was improvising. Reiner wanted a wild performance and Crystal certainly delivered. In fact, over the course of the three-day shoot in Max's home, the actor almost caused the production to be shut down completely because everyone was laughing so hard. Reiner allowed the actor the freedom to ad-lib as much as he liked. Elwes recalled:

"For three days straight and ten hours a day, Billy improvised thirteenth-century period jokes, never saying the same thing or the same line twice."

Crystal was so funny that it actually became a major issue for the cast and crew. Elwes, who had the difficult task of looking dead during every take, had to be replaced with a dummy at times because he simply could not keep himself from cracking up. Even Reiner had to leave the set because he had too much trouble containing his laughter. The only one who managed to hold it together was Mandy Patinkin, but he bruised a rib in the process. Imagine trying so hard not to laugh that you actually injure yourself! Actually, without Crystal's quick thinking, we never would've known how delicious an MLT is.

Let's also not forget about the incredible Carol Kane as Max's wife Valerie. The actress contributed just as much in making the scene so memorable. She not only held her own against Crystal's rapid-fire jokes, but also held it together well enough to volley back and forth with him. They really do seem like a couple that has been married for a very, very long time.

Comedy Is Like Jazz

Early in his career, Crystal was doing standup and working in improv-heavy environments like "Saturday Night Live," so ad-libbing was nothing new for the actor by the time he landed the role of Max in "The Princess Bride." He is known for his improv skills and has ad-libbed some famous lines in another one of Reiner's films, "When Harry Met Sally…" He had also previously worked with Reiner on other largely improvisational projects, including "This is Spinal Tap — in which he has a tiny, but memorable role — so the director knew Crystal could make Miracle Max stand out even among a cast of characters as amazing those who populate "The Princess Bride."

Crystal has actually been improvising since childhood. He told NPR:

"Even when I was in school shows, in elementary school doing plays, I'd always go off book and start improvising. Kids dressed as flowers would just look at me and think 'What is he doing?'"

Crystal was also inspired by hanging out with jazz musicians as a child. His uncle founded Commodore Records, and his father both owned a record store and produced jazz concerts. At a young age, Crystal was spending time with legends like Gene Krupa and Billie Holiday! He cites them as major influences on his style of improv, explaining:

"That's the thing about jazz: it's free flowing, it comes from your soul. I think when I feel I'm at my best is when I'm on stage, and it's my version of jazz because it's just riffing or something."

"The Princess Bride" will always be highly regarded for many reasons, not the least of which is fantastic performances from its entire cast. Crystal and Kane's roles may have been small in terms of the film's overall runtime, but their impact was huge.

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