Spoilers from the books and/or games to follow!
Lara Dorren aep Shiadhal was the daughter of Shiadhal and Auberon Muircetach. She was an elven sorceress who fell in love with Cregennan of Lod, a mighty human mage, after the Conjunction of the Spheres. Their union was very controversial for both races.
After Cregennan died, Lara gave birth to their daughter, but died herself soon after, orphaning the child. Cerro, the queen of Redania at the time, adopted the half-elf girl and named her Riannon.
The descendants of Lara Dorren, which include Ciri, are regarded as special, for their magical gifts are considered to be very strong as they carry Hen Ichaer, Elder Blood.
Andrzej Sapkowski 
Edit
Lara Dorren is also mentioned in Baptism of Fire through "The Tale of Lara Dorren" told by both humans and elves.
- "The queen replied: 'Ask not me for mercy, but those whom you wronged with your magic. You had the courage to commit those deeds, now have courage when your pursuers and justice are close at hand. It is not in my power to pardon your sins.' Then the witch hissed like a cat and her sinister eyes flashed. 'My end is nigh,' she shrieked, 'but yours is too, O Queen. You shall remember Lara Dorren and her curse in the hour of your dreadful death. And know this: my curse will hound your descendants unto the tenth generation.' Seeing, however, that a doughty heart was beating in the queen's breast, the evil elven witch ceased to malign her, or try to frighten her with the curse, but began instead to whine for help and mercy like a bitch dog... The Tale of Lara Dorren, as told by the humans"
- "... but her begging softened not the stony hearts of the Dh'oine, the merciless, cruel humans. So when Lara, now not begging for mercy for herself, but for her unborn child, caught hold of the carriage door, on the order of the queen the thuggish executioner struck with a sword and hacked off her fingers. And when a severe frost descended in the night, Lara breathed her last on the forested hilltop, giving birth to a tiny daughter, whom she protected with the remains of the warmth still flickering in her. And though she was surrounded by the blizzard, the night and the winter, spring suddenly bloomed on the hilltop and feainnewedd flowers blossomed. Even today do those flowers bloom in only two places: in Dol Blathanna and on the hilltop where Lara Dorren aep Shiadhal perished. The Tale of Lara Dorren, as told by the elves"
The Witcher Edit
During the game, Geralt can read two books that tell the elven and the human versions of the lovers' tale, Lara's Gift and The Story of Lara Dorren and Cragen of Lod.
It is suggested that Alvin might be a descendant of Lara Dorren.
