Daros, from Ultima VI
Daros is a sewer worker living in the dungeon beneath Castle Britannia.
The Avatar met him there in Ultima VI in the south-western area. Daros was a really strange fellow, insisting on calling the Avatar "Ducky", along with giving the Avatar a real rubber duck (it even squeaks!). Daros went on to speak about his job and the Giant Rats encountered in the sewers. He also recommended not swimming in the water, since it was quite nasty stuff.