Lord and Lady of LórienCeleborn, and his wife Galadriel who jointly ruled Lothlórien, the realm of the Galadhrim.
The Galadhrim were Silvan Elves, who were ruled by the Sindarin King of Lórien; after the loss of the last King Amroth in T.A. 1981, Celeborn and Galadriel came to rule the realm, although they renounced the royal title of "King" and "Queen".
Under them, the realm prospered for a millennium. With the power of Nenya, Galadriel kept the land pure and alive, and evil was not permitted to penetrate it. They built Caras Galadhon western across the Anduin where she planted the seeds of the mallorn trees that was given to her by Gil-galad.
During the War of the Ring they received the remnant of the Fellowship of the Ring, and also repulsed several assaults of Orcs from Dol Guldur, until eventually Celeborn counter-attacked, Galadriel threw down its walls, and Mirkwood was cleansed, making the southern part of the forest a province of their realm.