That leads to all sorts of questions. What should female trolls be called? Are they as sweet and lovely as Tove Jansson's "Snork Maiden" in the Moomintroll books?
According to http://www.whatson.is/default.asp?web_id=3&page_id=181 ,
"Female trolls were usually more benevolent than male trolls. The female trolls would often yearn for the love of humans luring men to their caves with magic spells. In many cases the men would fall in love with the trolls eventually becoming trolls them selves. Sometimes the trolls would have children with humans a sort of a half troll. These half trolls would generally look like ordinary humans possessing the magical powers of the troll parent. Female half trolls would often be exceedingly beautiful and enchanting."