The Faery Folklorist has posted a wonderful introduction to the trows of the Orkney and Shetland Islands. In case you’re not quite up to speed on your trow-lore, the article begins,
According to Saxby and Edmondston’s ‘Home of a Naturalist’ (1888), “This interesting race of supernatural beings is closely allied to the Scandinavian Trolls, but has some very distinctive characteristics of its own. The Trow is not such a mischief-making sprite as the Troll, is more human-like in some respects, and his nature seems cast in a morbid, melancholy mould.”
From there, the article discusses what trows look like, where they live, and the sorts of things they do. There is even a brief but delightful list of trow names culled from Orkney and Shetland folklore.