Walt Disney: because Disney’s just such a Gestalt thing, you know? Not just the toon characters, but the breakthroughs in animation, the Disney style of animation, the marketing-genius theme parks, the TV productions, the much-imitated merchandising, etc. And I say this as a life-long fan of all things Warner Bros. (Alternate picks: muppet-master Jim Henson; Warner animators Freling, Jones).
George Gershwin: composer, pianist.
Louis Armstrong/Charlie Parker/Miles Davis will have their advocates.
Irving Berlin: extremely prolific songwriter (“White Christmas”) from the Tin Pan Alley era.
Nathaniel Hawthorne: supposedly the first American fiction writer who made his living from his writing. Yeah, I prefer Poe (who doesn’t?), but N.H. was historically and literarily significant and groundbreaking in his own right – who with his penchant for Gothic horror, often comes across as an Ur-Poe.
Ben Hecht: very important and prolific screenwriter (also directed, produced, and tried his hand at novel-writing). One of the great relatively-unknown workhorses of Hollywood history.
Clint Eastwood: actor, director, jazz pianist/composer/festival promoter. Has even been known to sing on occasion. He would look good in granite, too.
Frank Sinatra: singer, actor. Was always as tough as granite.
Chuck Berry: may be disliked for his sexual peccadillos and run-ins with the law, but if any one individual can be said to have invented rock-'n-roll, he did. Besides, it’s not as if Sinatra was an angel or anything…
Woody Allen: again, it’s a Gestalt… from doing stand-up and comedic writing (all those “New Yorker” pieces, later collated in books), to acting, screenwriting, directing (usually all at once), and his famous Tuesday nights at Joe’s Pub. Granted, Woody was borrowing from S.J. Perelman, Groucho & Harpo Marx, and Jack Benny, but he did forge his own brand, as it were.