Lynesse Hightower is an unseen character in Game of Thrones. She is the former wife of Ser Jorah Mormont, the former Lord of Bear Island, and a member of House Hightower of Oldtown. She's the younger sister of Alerie Tyrell, the wife of Lord Mace Tyrell.
In the books
Lynesse married Jorah Mormont after he won a tournament to celebrate the victory of King Robert against the Greyjoy Rebellion, in which Jorah wore her favor. Lynesse was used to the riches and luxury of the second-largest city in Westeros, and found Bear Island primitive and rude. Jorah's attempts to please his wife led to him spending all of his money. He disgraced himself through behavior unbefitting a lord, by arresting poachers and selling them to slavers. Slavery is illegal in the Seven Kingdoms and has been for millennia. When Eddard Stark came to arrest Jorah, he and Lynesse fled across the Narrow Sea to the Free City of Lys, leaving his aunt Maege to become the ruling Lady of Bear Island. Jorah attempted to make his living as a sellsword, but was unable to provide an income acceptable to Lynesse. She left him and became a concubine to the merchant lord Tregar Oromollen.