1947, D. Gottlieb & Co.
Humpty Dumpty was the first pinball machine with flippers, though unlike later models, its flippers faced outward, making it much more difficult to play. On the other hand, it did have six of them.
This was especially important at the time because of the bans many cities (including New York, LA and Chicago) had placed on pinball, as it was believed to be a form of gambling. The flippers added a layer of skill and helped contribute to the game's eventual unbanning.