From left: E.T. inspirations Albert Einstein, Carl Sandburg and Ernest Hemingway
Coming up with the look of E.T. was a difficult task. Spielberg’s first concern was that the star-hopping creature not look like traditional depictions of aliens — specifying a look “so anatomically different that the audience would never be able to think that there was a person in a suit with a zipper up the back.” Screenwriter Mathison imagined the extraterrestrial as being “squishy, earthy, muddy” — consistent with his being some sort of botanical specialist.
In the end, the director reached out to special-effects wizard Carlos Rimbaldi, with whom he had worked with on Close Encounters of the Third Kind, to help with the design. As they worked toward the final version, Spielberg was reportedly much moved and influenced by photographic portraits of Albert Einstein and writers Ernest Hemingway and Carl Sandburg. E.T.’s voice was created by sound-effects legend Ben Burtt, who utilized a variety of voices (including, most famously, actress Debra Winger) and animal sounds (like raccoons and horses) but primarily used lines read by an elderly woman whose perfectly raspy voice came from a lifelong two-packs-a-day cigarette habit.
(MORE: TIME Talks to Legendary Creature Creator Rick Baker)