Galadriel is an Elf from the Tolkienverse. Wedded to Celeborn, she is the mother of Celebrían (the real one, not to be confused with the imposter in the Legendary Badfic of the same title), and the grandmother of Arwen Undomiel. Tall and beautiful, her golden hair is legendary, and she famously gifted Gimli the Dwarf with three strands of it. She and her husband ruled Lothlorien together, and she bore one Ring of Power, Nenya.
In Suefic, Galadriel often exists only to make prophecies about how special the Sue is, as well as shower her with praise. That, or it turns out that she is the Sue's mother and that the Sue was transported to Earth long ago. Sometimes, Elrond turns out to be the father (even though as mentioned, Galadriel is his mother-in-law). In other Suefics, Galadriel turns out to be evil and jealous of the Sue. Those fics often have Haldir be the Sue's father and the true King of Lorien.