Mercedes Ritchie Lackey is an American writer of fantasy novels, born on June 24, 1950. She is renowned for her expansive body of work, having published over 140 books. Many of her novels and trilogies are interlinked and set in the world of Velgarth, primarily in and around the country of Valdemar.

Her Valdemar novels include interactions between human and non-human protagonists with a variety of cultures and social mores. Another notable world she has created is similar to Earth, featuring clandestine populations of elves, mages, vampires, and other mythical beings.

The Bedlam's Bard books describe a young man with the power to work magic through music; the SERRAted Edge books are about racecar driving elves; and the Diana Tregarde thrillers focus on a Wiccan who combats evil.

Lackey has also published several novels that rework well-known fairy tales. These are set in a mid-19th to early 20th-century setting where magic is real, though hidden from the mundane world. Her stories explore themes such as ecology, social class, and gender roles.

She has been described as one of the "most prolific science fiction and fantasy writers of all time" and was named the 38th Damon Knight Grand Master in 2021.