Nintendo has made six consoles since 1983, each with a distinctive controller. One constant through all these years, as you can see in this .gif from Gadgetlove, is the plus-shaped directional pad.
The Intellivision sported a circular, 16-direction pad but the overall ergonomics of the controller put many users off, especially next to the simplicity of the Atari VCS' joystick. So when the first Nintendo Entertainment Systems arrived in the United States, some here were skeptical of a system which had no stick to control. That skepticism swiftly vanished.
Another constant? A button labeled "A." The B button was an unlabeled red button next to A on the GameCube, and was then the trigger on the underside of the Wii Remote, before returning on the Wii U GamePad. Otherwise, it too would be part of a controller design that has been both innovative and remarkably consistent for more than 30 years.
Gadgetlove features a larger-resolution, interactive animation allowing you to cycle back and forth through through the morph to see it change over the years. They've also done animations for the PlayStation controller, the Xbox's, and the changes made to the iPhone. Go check ‘em out.