This is a list of books by Mercedes Lackey, arranged by collection.
Valdemar universe.
Some of the trilogies follow on chronologically from each other, while others are set a considerable number of years apart from the others—overall the books span some 2500 years.
"The Mage Wars".
Co-written with Larry Dixon. These are set in pre-history, some 2500 years before the "Heralds of Valdemar" trilogy. They describe the events which set off the Mage Storms. It involves gryphons, creatures created by the mage Urtho (Mage of Silence). The co-protagonists are Skandranon Rashkae, a princely but proud ebony gryphon, and Amberdrake, a Healer of spirit and mind called a kestra'chern.
"The Founding of Valdemar".
The story of the Baron Kordas Valdemar fleeing with his people the oppressive Eastern Empire and founding the kingdom of Valdemar in the western wilds. The trilogy takes place c. 1000 years after "The Mage Wars" and some 1400 years before the original "Arrows" trilogy.
"The Last Herald-Mage".
These occur some centuries before the "Heralds of Valdemar" books, telling the life story of Vanyel Ashkevron; by the time of the "later" books he has become legend, thus explaining some of the small inconsistencies. This series was also consistently nominated for the Lambda Literary Prize, with "Magic's Price" winning in 1990. As of 2021, the novels in the Last Herald-Mage trilogy are in development as the first season of a television show based on the Valdemar universe adapted by Kit Williamson and Brittany Cavallaro with Ted Field, Anthony Tringali, Michael Napoliello, and Maria Frisk at Radar Pictures executive-producing. This will be the first live action adaptation of Lackey's work.
"Collegium Chronicles".
This series marked Lackey's novel-length return to Valdemar after a five-year hiatus. The series takes place about a half a century after "Magic's Price" and about 500 years before the "Heralds of Valdemar" books and tells about the time of the founding of the Heralds' Collegium.
"The Herald Spy".
This series is a continuation of the story of Mags from the "Collegium Chronicles". It covers Mags' journey as a full herald and a spy.
"Valdemar: Family Spies".
This series is a continuation of the story of Mags after "The Herald Spy" trilogy. It follows Mags and his children as they learn the family business.
"Brightly Burning".
"Brightly Burning" (May 2000) is a stand-alone novel, set somewhere between "Collegium Chronicles" and the "Heralds of Valdemar" books; it describes another legendary character briefly referred to in the latter, "Lavan Firestorm".
"Vows and Honor".
These precede the "Heralds of Valdemar" books and center around the characters Tarma and Kethry. These characters appeared first in Marion Zimmer Bradley's Sword and Sorceress series and were revisited in subsequent short stories. Two of these short stories are woven into the "Vows and Honor" books as part of a longer narrative. The original "Vows and Honor" pair of books were linked together with "By the Sword" (published long before "Oathblood") as a trilogy.
The third volume, "Oathblood", is made up entirely of short stories in place of a longer narrative. With its publication, nearly all of the Tarma and Kethry stories were available together in a single compiled volume for the first time. The single missing story, "A Dragon in Distress", was co-authored with Elisabeth Waters and was originally published in the "Sword and Sorceress" series, volume XII. The story, now available as a solo e-book, is missing from the "Oathblood" collection due to being set in Elisabeth Waters's world, not Mercedes Lackey's Valdemar.
The contents of "Oathblood" are as follows:
In the books and short stories, Tarma is a sword-wielding Shin'a'in clanswoman. Kethry is a magic-user who carries a sword with unusual properties. The nature of this sword, Need, is explored in later series set in Valdemar. At the time of the "Vows and Honor" books, all that is known is that it is magic, protects female bearers, and can pressure its owner into assisting other women. The overarching goal for the two women is to accumulate resources enough to regenerate Tarma's almost-destroyed clan. As the titles of the books suggest, emphasis is laid on the importance and consequences of oaths in at least one story from each book. The setting of the books is generally in the lands south of Valdemar such as Rethwellan, although there is a brief sojourn in Valdemar in "Oathbreakers". Despite limited time in Valdemar, there were references in the first two "Vows and Honor" books to the Companions of Valdemar which laid early hints to their nature. The introduction of a fourfold deity (Tarma's Goddess) was something of a novel idea at the time of publication.
"Kerowyn's Tale".
This is a stand-alone novel which connects the "Vows &amp; Honor" sub-series to the "Heralds" and other trilogies; it introduces the character Kerowyn, who is the granddaughter of Kethry from the "Vows and Honor" sub-series.
"Heralds of Valdemar".
This set consists of the original trilogy, the very first Valdemar books published, and a prequel trilogy.
"Heralds of Valdemar" prequels.
These center on the Weaponsmaster Alberich (in the first two books) and the thief Skif (in the third book), telling the stories of their not-entirely-voluntary enrollments as Heralds. The order in which they were written differs from the internal chronology.
"Arrows" trilogy.
The first written and published of the Valdemar novels, these center on the character Talia, who from the moment of being Chosen by her Companion Rolan becomes the special and hard-working Queen's Own Herald.
"The Mage Winds".
These follow on from the original "Heralds of Valdemar" trilogy and center on Princess Elspeth completing her transformation from "the Brat" to a fully-fledged Herald. Secondary protagonists include Skif and a new character, Darkwind.
The latter part of "Kerowyn's Tale", "By the Sword", fills in the events that happen after "Arrow's Fall" but before "Winds of Fate".
"The Mage Storms".
This next trilogy follows on the "Heralds of Valdemar" story and centers around the characters Karal and An'desha as Velgarth is threatened by a repetition of the Cataclysm described in "The Mage Wars" trilogy. This trilogy also focuses on the threat posed to Valdemar by the vast Eastern Empire and the development of the newly formed Alliance between Valdemar and its surrounding nations.
"Darian's Tale".
The "Owl" trilogy takes place several years after the events of "The Mage Storms" and follows the character Darian. The story focuses on the repercussions of the mage storms on Valdemar's northern border and centers on new tensions between the Kingdom and invading barbarians from beyond the Ice Wall.
"Kelvren's Saga".
The setting of this miniseries of shorter fiction and a novel to be published in 2023 is a post–Mage Storms military conflict with a "secessionist" movement in Deedun. The series features the character Kelvren Skothkar from the preceding series "Darian's Tale".
Anthologies and other publications.
Various anthologies have been published from 1997 featuring some short stories by Lackey and other authors she invited to write about the Valdemar universe. A companion book was also produced about the universe.
Elves on the Road universe.
This universe is set in warp-modern time featuring elves and magic.
Bedlam's Bard.
Lackey wrote the first few in this series with Ellen Guon and the latter part with Rosemary Edghill.
 "Bedlam's Bard" (1998)—compilation of "Knight of Ghosts and Shadows" and "Summoned to Tourney"
 "A Host of Furious Fancies"—compilation of "Beyond World's End" and "Spirits White as Lightning"
When reading the series in chronological order, "Music to My Sorrow" follows directly from "Mad Maudlin".
Diana Tregarde.
The main character, Diana Tregarde, is an American witch, practicing a fantasy version of Wicca; by virtue of her position as a "Guardian" Diana has access to more magical power than many and she is required to give her help when someone asks it of her. Her magical abilities do not pay the bills, however, and so Diana makes her living by writing romance novels. In the stories, Diana must protect others from angry deities, vampires and a sorceress who intends to remain eternally young.
The character Diana Tregarde first appeared in two short stories, "Satanic, Versus..." and "Nightside", which were originally written for inclusion in the "Bureau 13: Stalking the Night Fantastic" roleplaying game. The short stories were first published in "Marion Zimmer Bradley's Fantasy Magazine":
The books were published under Tor's horror imprint rather than its fantasy one. At the time of publication, positive depictions of what Wiccans and, more generally, neopagans believed and did were rare. In the mid-nineties, Lackey's books generally were regularly cited as examples of pagan-friendly fiction. Lackey wrote that she had no plans for further books in the series because they did not sell well; nonetheless, she incorporated several elements of the Guardian mythos, including the apartment building where Diana lived, into later books in her "Bedlam's Bard" series.
In the collection "Bedlam's Edge" Lackey notes that she placed the Diana Tregarde world with her "SERRAted Edge" and "Summoned to Tourney" world with the intention of forcing anyone who believed Diana Tregarde and the Guardians were real to also have to believe in elves, dragons, and other patently fantastical things.
The SERRAted Edge.
The SERRAted Edge: Doubled Edge.
The Doubled Edge series is set several hundred years earlier than the other SERRAted edge books. The storyline is historically based, surrounding Elizabeth I's parentage, birth, and rise to power. In the fictional series, the Light court elves try to bring Elizabeth safely to the throne, while the Dark court elves hope for the misery of religious persecution from her half-sister Mary. "This Scepter'd Isle" revolves around Henry VIII's illegitimate son Henry FitzRoy, 1st Duke of Richmond and Somerset, and the later three focus on Elizabeth.
"Sacred Ground".
"Sacred Ground" (1995) is a non-series contemporary novel about Native American magic. The main character, Jennifer Talldeer, is a private investigator. She is also Kestral-Hunts-Alone, an apprentice shaman learning modified tribal magic from her grandfather. She is called in to investigate possible sabotage at a local construction site where Indian artifacts have been found. 
In her short story "After Midnight" Lackey implies that the novel was an attempt to recover the spirit of the Diana Tregarde novels after the fiasco with a few fans believing the novels were based on real events. However, "Sacred Ground" also did not sell well, and Lackey took a break from dark fantasy.
"Drums" (2010) is a novella included in "Trio of Sorcery" (2010)
Heirs of Alexandria series.
The first books in this series were featured on various Baen CDs. In 2010 Baen CD 23 featuring included The Shadow of the Lion, "A Mankind Witch", "This Rough Magic", and "Much Fall of Blood" of the Heirs of Alexandria series among other books.
The Secret World Chronicle.
The "Secret World Chronicle" is a series of "braided novels," based on characters and ideas created by Lackey and Libbey in an on-line role-playing environment, transposed into an entirely new setting. Although there are plans to set future works in different eras, "Invasion" is set in the present-day in a world where "metas" (short for metahumans, that setting's term for superheroes) first appeared during World War II and now play an important role in keeping the world safe. In "Invasion," the world is invaded by a mysterious force of armored Nazi soldiers, from the disbanded arcane Thule Society, some of whom are subsequently found not to be human.
While the "Secret World Chronicle" is not set in the same world as the "SERRAted Edge" and "Bedlam's Bard" series, it does share certain elements in common with those books: one of "Invasion"'s central characters, Victoria Victrix Nagy, is referred to as a Knight of Underhill.
The first book of the "Secret World Chronicle" began serialization in podcast form in September 2006, read aloud by actors Adam Higgins and Laura Patterson. Beginning in 2007, the series continued to be read by voiceover artist Veronica Giguere. In the second quarter of 2009, the series was sold to Baen Books with a publication date of 2011 for the first book and 2012 for the second.
According to Lackey's website, the four published books are "Invasion" (2011), "World Divided" (2012), "Revolution" (2013), and "Collision" (2015), with two short stories – "Secret World War: White Bird" and "Secret World War: Sgian Dubh –" also available. A fifth book, "Avalanche", was released in August 2018.
The Halfblood Chronicles with Andre Norton.
This series of novels is set on a world where both elves and dragons arrived from dimensional portals onto a world where humans were native. The dragons remained hidden and elves subjugated the humans. The story follows the exploits of a group of half-blooded humans attempting to fight the elves.
Elemental Masters.
Set in an earth where magic exists during the early 20th century,