I've been on a Dragon Quest kick recently so these are a few who are fresh in my mind:
-An old man in DQ9 is trying to push his whole ass house just a bit to the left, and he says he can do it if you give him a ring of strength, which is kinda expensive at that point in the game. If you give it to him he does this big show of strength as he presses against the house, and after a moment of no change he goes "there. One inch more for my garden" very funny to me
-A bunny girl in DQ9 who is in the middle of nowhere in the mountains chilling at the bottom of a well. She says she was going for a jog that started on a different continent before she broke a heel on her shoe and cannot run back. She asks for super rare metal slime boots, and if you give them to her she says she actually was gonna rob someplace and runs away at impossible speed
-Talking horse from DQ4
-Sheep that cannot talk but asks you for a favor anyway from DQ9

Honorary mention to Torneko Taloon DQ4 who was a shopkeeper NPC, but decides to go on a quest to earn 1 William dollars and eventually bankrolls the hero's quest in the final act.