The NES bought a lot of genres that weren't very well known into the mainstream. One such genre was the J-RPG, which has had massive successes since.
Dragon Warrior was released by Nintendo in 1989. It's known as Dragon Quest in Japan and is widely known as the best selling J-RPG game of all time, even going as far, as causing Japan to grind to a halt when new games are released.
RPGs were still a very very niche genre when Dragon Warrior was released. However, a massive Nintendo Power campaign secured this game's place in gaming history forever. The game is a very traditional grind-fest style of RPG, requiring in depth knowledge of inventory management and tactical planning. Gamers who found themselves used to the Legend of Zelda style found themselves woefully outclassed by the game, as unwary adventurers would leave a town and usually get killed by the first enemy they found.