Several noble houses have held the title since the War of Conquest. After the death of Harren the Black and his sons, Aegon the Conqueror granted the castle to House Qoherys as a reward for its loyalty until the line died out. The following families to rule Harrenhal were the Towers, Harroways, Strongs, and Lothstons, all of which became extinct, leading to the popular belief that the castle is cursed. Following House Lothston, the Whents become the new Lords of Harrenhal, until the castle is occupied by House Lannister during the early stage of the War of the Five Kings, while Lady Shella Whent flees from it.
The title of Lord of Harrenhal is then awarded to Janos Slynt, commander of the City Watch of King's Landing, for his role in the betrayal and arrest of Eddard Stark. Thus, the newly created House Slynt displaces the nigh-extinct House Whent. However, Lord Janos never takes possession of Harrenhal, as he's stripped of lands and title and exiled to the Wall.
Tyrion Lannister then offers the title to Petyr Baelish in exchange for his aid in the liberation of Ser Jaime Lannister, along with the title of Lord Paramount of the Riverlands. However, Baelish obtains Harrenhal from the hands of King Joffrey as a reward for arranging an alliance between Houses Lannister and Tyrell.