4. Rear Window
Speaking of the Chipmunks, creator Ross Bagdasarian was actually playing himself in the Alfred Hitchcock classic Rear Window as a struggling musician/songwriter. As the hobbled Jimmy Stewart peers into his apartment from across the New York City alley with his binoculars, Bagdasarian is shown in long takes banging away at his piano trying to come up with a hit song, a frustration the real-life Bagdasarian knew all too well. Years later, he would invent the Chipmunks, and the rest is (annoyingly harmonizing) history. And, as always in his films, Hitchcock himself makes a cameo appearance in the background of Bagdasarian's room, winding his clock.