R.O.B. (Robotic Operating Buddy) is an accessory for the Nintendo Entertainment System. It was released in July 1985 in Japan as the Family Computer Robot and later that year in North America as R.O.B. It had a short product lifespan, with support for only two games which comprised the "Robot Series"; Gyromite and Stack-Up. R.O.B. was released with the intention of portraying the Nintendo Entertainment System as something novel in order to alleviate retail fears following the video game crash of 1983. R.O.B. was available in the Deluxe Set, a configuration for the console that included, among other things, R.O.B. and Gyromite. Stack-Up was purchased separately and included its own physical game pieces.
Source: Wikipedia, R.O.B., available under the CC-BY-SA License.