Dragon Quest (1986, NES)
This first visit of the epic series to the land of Alefgard has a lone hero battling the Dragonlord in order to save the rather oddly named damsel in distress Gwaelin.
Dragon Quest II: Pantheon of Evil Spirits (1987, NES)
Introduces multiple party members so that you don’t have to face the gargantuan killing machine that is, erm, Slime, alone. You get a boat too.
Dragon Quest III: And Into the Legend... (1988, NES)
Sold six million copies, making it the most successful Quest ever. Character class and skill system set the standard for that kind of thing.
Dragon Quest IV: The People Who are Shown the Way (1990, NES)
Tricky narrative that told the tale of four people who would help you later in the game. Bit like Pulp Fiction, only with less gimp.