In Game of Thrones/A Song of Ice and Fire by George R. R. Martin, Lyanna Stark was the sister of Eddard Stark. She died before the beginning of the stories. She was bethrothed to Robert Baratheon, but she was kidnapped by Rhaegar Targaryen. When her father demanded justice from King Aerys II, the King had him and her brother Brandon Stark executed. In retaliation, Eddard and Robert joined with other houses to overthrow the Targaryens.
Lyanna Mormont was named after Lyanna Stark, and was the Lady of Bear Island, and cousin of Jorah Mormont. In the television series, she pledged what few men she had to support Jon Snow and Sansa Stark in their bid to take back Winterfell from the Boltons.
Lyanna is also the name of a character in The Chronicles of the Raven by James Barclay. She was the daughter on Erienne Malanvai and the mage Denser.
Lyanna could be a variation of Liana, which has origins in multiple languages. In 2014, 58 girls in the United States were named Lyanna.