Fomor

The Fomor are an ancient race of water-dwelling creatures. They've appeared in the short stories: "Even Hand",  "Aftermath" and "Bombshells". They've also been mentioned in Ghost Story and Cold Days, and appeared in Skin Game.

Description
They are "exiles from myth and legend, the outcasts of the gods and demons of every land bordering the sea. Defeated giants, fallen gods, dark reflections of beings of light. They are many races and none, joined together beneath the banner of the Fomor in a common cause." Their common cause is revenge.

By the appearance in Aftermath, Fomors are man-shaped of medium height, sallow skin, greasy black hair and an extremely wide mouth. They have dark, watery, bulging eyes, small sunken noses, long scrawny limbs, and very, very wide hands. They also have flaps of skin on their neck that they breathe air from. They look like a vicious frog, earning them the sobriquet "Frog Men".

The Fomor Mag that appeared in Even Hand was also frog like, tall with wide lips. As is the Fomor that appears Bombshells. Its very likely they all share this froglike appearance.

It is stated that their abilities include sorcery, shapeshifting and clairvoyance. They practice entropy magic, and are not hampered by running water like most magic users. They give off a heavy anti-technology field.

They are weakened by iron, as they often interbred with the Fae "before the Sidhe Wars."

They rarely deal with humans and appear to be ruthless and everyhere. They have been known to trade their handywork for favors and influence. For some reason, the Fomor are especially prone to giving long winded, gloating, self praising monologues. They are probably the creators of the beasts used by the Denarians.

They are signitories of the Unseelie Accords. They are led by a man named King Corb, whose court is located in Lake Michigan. They are related to Jotuns.

The Fomor easily have the resources to withstand the severely downsized Wardens, who have lost many of their best from the war with the Red Court. They have successfully kidnapped and murdered many of the less talented practitioners, who are now relying on the Paranet to stay safe, and the Wardens are too short handed to do much about this. The Fomor have prominent postitions in most large cities in the USA and Europe as we are told in Aftermath and Even Hand. Although we are told in Cold Days that Carlos Ramirez was severely injured and Wild Bill Meyers has been "giving them Hell". They, however, do not have the resources to remove the Brighter Future Society, also called the Chicago Alliance. (Ref?)

They are known to use sea urchin-like projectiles that spew acid, and nuclear sea-shell bombs as weapons.

History
Bob told Harry Dresden and Waldo Butters that before the time of the Sidhe Wars, there were all kinds of stories about the Fomor, the Daoine Sidhe, the Tuatha, the Tylwyth Teg, and the Shen—there were epic alliances, epic betrayals, epic battles and epic weddings.

The Leanansidhe said that they were once the enemies of her people, both Winter and Summer courts. The Sidhe banished them to to the sea.

"Aftermath"
In Aftermath, within hours of the fall of the Red Court, groups like the Fomor began to try to seize power and engage in genocidal tactics similar to those employed by Vittorio Malvora; only the Fomor do not kill, they twist and enslave.

Ghost Story
In Ghost Story, their advances into the states and cities bordering large bodies of water have been the motivation for Baron John Marcone forming the Chicago Alliance between the Paranet, the Alphas, the Brighter Future Society, the outfit, the Einherjaren, and local White Court nobles. Their goal is revenge and therefore they seek power as their means—made easier to garner by the demise of the Red Court.

Cold Days
As of Cold Days, the Fomor have a strong foothold in Los Angeles, Seattle, Miami, and Boston. The White Council is fighting them mainly in Europe, and are at a stalemate. In the USA the Wardens in Baltimore, San Diego, and especially Wild Bill in Texas are fighting them off. In Chicago Karrin Murphy, Lara Raith and Gentleman Marcone and their people together have also pushed them out.

"Aftermath"
In Aftermath, when Fomor Servitors kidnap Georgia and Andi, William Borden asks Murphy's help to get her back.

Ghost Story
In Ghost Story, Abby reported at the Chicago Alliance meeting that there missing Paranetters in Oregon, they fear that the Fomor has abducted them. Murphy told Harry's ghost how they pushed back a fomor incursion since his death. Butters told Harry's ghost how Molly has made the difference between life and death in two battles against the Formor. and, how the Netters need the Chicago Alliance Headquarters as a safe place from the Fomor. Molly fights a pack of their Servitors as part of Lea's combat training. Molly told Harry's ghost what the Fomor and their Servitors have been doing, how they hurt and kidnap people even children. Harry eavesdrops on the Grey Ghost (aka Corpsetaker) discussing her bargain with the Fomor's Lord Omogh with his servitor, Listen. Lea told Harry that the Sidhe banished them.

Cold Days
In Cold Days, Thomas informed Harry that the Fomor situation is the worst in the cities of: Los Angeles, Seattle, San Francisco, Miami and Boston. They have not gotten a solid foothold in Chicago because of Karrin Murphy's people, Johnny Marcone's people and Lara Raith's people.

Basis in mythology
(largely taken from Fomor)

Fomor (or "Fomorians") are a race of sea-based gods in Celtic lore. They are hypothesised to have been in Ireland before Partholon's invasion of Ireland, and engaged in long wars with the newcomers - Partholon's army, followed by his decendents the Nemedians, then the Fir Bolg, and lastly the Tuatha de Danaan. They are generally considered to represent the older native gods of Ireland, similar to the Greek Titans or Norse Jotunn. They are constantly defeated, in myth, but are never entirely vanquished; they're the equivalent of Celtic cockroaches. If cockroaches were amphibian magical badasses.

Arguably the most well-known Fomor of myth is Bres, the half-Fomor half-Tuatha who was given the role as the first High King of Ireland, in the hopes of finally uniting the two warring races. He turned out to be a tyrant who favored his Fomorian side, and was overthrown after a seven-year reign. His later defeat and death, by Lugh, forced the remaining Fomor to give up, and they allegedly return to sea.

External references

 * Fomorians - Wikipedia
 * Mystical Mythology from around the world
 * Ireland’s First Mythical Inhabitants: The Fomorians | Faerie Lore
 * The Fomorians - Irish Mythology Wiki
 * Fomorians - Encyclopedia Mythica
 * Fomorians - shee-eire.com
 * Jötunn - Wikipedia, the free encyclopedia
 * Jötunn - Mythology Wiki
 * Jotuns Norse Mythology