The saltiest sea wench around, a former assassin/prostitute who now captains the party's boat. The party rescued her from slavery and she quickly became indispensable to their operation. Ros often handles the business end of things, making deals and organizing the day to day affairs of the boat and the party's money.
Ros is in (what appears to be, despite what you would think) a monogamous relationship with Thom the Dragonborn. She did give him VD though.