Heinrich Kemmler

Heinrich Kemmler was a male human necromancer. He was first mentioned in Dead Beat.

Description
"The master wrote down his teachings, wizard, so that those who came after him could learn from him. Could learn about the true power of magic."

- Evil Bob on the contents of The Word of Kemmler.

Kemmler is considered to be one of the most powerful warlocks and necromancers of all time. He practiced what he called 'true magic' to control life and death. His main focus was necromancy, for which he was renowned. He was deemed such a risk that the entire White Council hunted him down in 1961.

Despite not understanding morality, Bob said Kemmler was sick, evil and insane. Mab referred to him as a madman and a monster.

Kemmler owned Bob for forty years, during which time his mindset was warped considerably. Bob later forgot most of this time, either by choice or by compulsion.

He had power over the dead and demons, was allied with most of the vampire courts, every "nasty" in Europe, and some of the more malicious Faeries. He had his own cadre of apprentices and thugs, called "Baby Kemmlers" by Harry Dresden, who followed him in his footsteps and practiced the darker arts.

Kemmler had learned a way to bind his will to shades as well as the dead, to devour them in order to feed his own power. This was what allowed him to defy the White Council for so long. This secret of using ancient spirits for the Darkhallow is written in The Word of Kemmler.

He wrote and self-published a number of magical texts: The Word of Heinrich Kemmler, The Blood of Kemmler, The Mind of Kemmler and The Heart of Kemmler.

He was attempting the Darkhallow ritual when he was defeated by the White Council.

Biography
Kemmler has been killed by the White Council seven times over the course of a number of wars with him. The first being in 1890's, the second near the end of WW2 and most recently in 1961. It was during this last attempt that the entire White Council down to the last wizard was devoted to killing him.

He was responsible for World War I. There was about 150 years of history behind it and Kemmler had his hand in several facets of it. He vanished after WWI then reappeared in WWII when he animated mass graves and rampaged through Eastern Europe. It's uncertain how many he actually killed.

Justin DuMorne, a Warden at the time that the council destroyed Kemmler, pulled Bob out of the ruins of Kemmler's lab, recognizing the spirit of intellect and wanting it for his own uses. Bob was later recovered by Harry Dresden after his final confrontation with DuMorne.

"A Fistful of Warlocks"
In "A Fistful of Warlocks", Kemmler challenges Anastasia Luccio to follow her outside the Long Branch Dance Hall and Saloon; Luccio refuses. Later, he is performing a zombie-animating ritual to be used in the fight with Luccio and Wyatt Earp, until he's interrupted by them.

Ghost Story
In Ghost Story, during a conversation with Evil Bob, Harry Dresden was told that Kemmler would have been interested in him as a disciple, implying that they may have been similar when younger.

Kemmler is mentioned because one of Kemmler's Heirs—Corpsetaker—is back as the Grey Ghost seeking to take over Mortimer Lindquist's body by torturing him into giving his consent.

Cold Days
In Cold Days, Harry Dresden learns from Bob that Halloween night is the only time that the Darkhallow could turn a wizard into an Immortal since. This is because Halloween Night is the only time of the year when the "locked stasis of immortality becomes malleable"—they can add new power to their mantles of immortality by feeding: taking in new energy. He also learn that Halloween is the only time they are vulnerable to being killed.

The Heirs of Kemmler
The Heirs of Kemmler intend to call up ancients spirits using the Erlking and then devour them for power on Halloween Night during the powerful Darkhallow spell that will turn one of them into a god-like being with ungodly powers.

Darkhallow
The Darkhallow is a ritual whereby one elevates themselves to near godlike power using necromancy. Kemmler attempted the Darkhallow, as did Cowl. However neither were successful.

The Darkhallow can only be attempted successfully on Halloween night.