Grimness is a cliff-girt headland on the island of South Ronaldsay, in the Orkney archipelago of Scotland. It is located between Honeysgeo and Skipi Geo and rises to a height of 34 metres above sea level. There is a trig point at the summit. The name is from the Old Norse and means Grim's headland.^[1][2] There are various small skerries offshore including Skerrilee, Scarf Taing, The Keys, Grey Chair, Out Hillock, Broddebb and Stack of Kame. There is a small geo (inlet) in the southern facing cliff known as Sheep Bight. There is a single farm called Head.

The Ordnance Survey grid reference is ND490928.^[3]