Cowl

Cowl is a human wizard and necromancer. He first appears in Grave Peril and is named in Dead Beat.

Description
"I do not perceive myself to be mad. But if I were truly mad, would I be able to tell?"

- Cowl to Harry Dresden

Cowl is an unknown, extremely powerful wizard, who is power-hungry, but seemingly sane. He may actually be one of the wizards on the White Council, or someone entirely different. His face has never been seen, and his real name is unknown. Cowl informs Harry that "The Council is not what it once was. It's rotted from the inside, and many wizards who have chafed at its restrictions have seen the War with the Red Court reveal its weakness. It will fall. Soon."

In Dead Beat, he attempted to gain the power of a minor god with the Darkhallow ritual. Bob believes that Cowl knew that Halloween is the only time to perform the Darkhallow. Bob said of Cowl, "That guy is seriously scary."

Cowl and Kumori were dressed nearly identically in long black robes, long black cape, big black mantles, big black hoods which revealed nothing of their faces.

Cowl stated that "a great many things of significance happened that night" at Bianca's Ball, the majority of which Harry is not aware of yet.

When Harry calls Cowl a Kemmlerite, his answer was of disdain for the madman Kemmler.

He's been associated with his subordinate Kumori, Vittorio Malvora (who was working with Madrigal Raith) and part of the Circle, which might indicate his membership to the Black Council.

Powers
Harry judged that his power was Senior Council level; Cowl hit him harder than Ebenezar or the Leanansidhe.

Cowl's magic is described as not necessarily black, and human, but tainted like Harry's. He's a powerful necromancer, though he denies being one of Kemmler's disciples.

His skills at opening up portals to the Nevernever are better than Harry's and he is also able to close other practitioner's portals from a distance. He can sense other practitioners from a distance.

Cowl can appear to be something he's not—he came up behind Harry as a zombie lifting his spear, then shimmered into his robed self and threw out a spell at Carlos Ramirez that threw him twenty feet. Then he quickly blocks a Hellfire-strengthened kinetic blast that Harry aims at him by crossing his arms in an x-shape, which only put him off balance.

Grave Peril
In Grave Peril, two unnamed hooded figures, fitting the description of Cowl and Kumori, appeared at Bianca's Ball. One of them held out to Ferrovax a small cask about the size of a breadbox, opened it—"the lights gleamed on something that sparked and shone." They also handed the box containing Morgana's athame to Bianca to give to the Leanansidhe.

Dead Beat
In Dead Beat, Harry Dresden meets Cowl for the second time, where he's searching for Die Lied der Erlking and The Word of Kemmler with Kumori, his assistant. Harry recognized them from Bianca's Ball as the ones who gave Leanansidhe the athame. Harry flips a car onto him and manages to escape with the aid of Billy Borden and the Alphas. Cowl knew that Harry possessed Bob the skull, and took it in order to learn how to perform the Darkhallow. With Bob, he had no need for the Word of Kemmler. Cowl disappeared after the workings of the Darkhollow were disrupted.

At the end, Dresden informs Donald Morgan and Joseph Listens-to-Wind that he thinks Cowl had a deal with the Reds to keep the Council busy while he performed the Darkhallow. The Reds would get the Senior Council out of the deal. Morgan thought the Edinburgh defenses were nearly impenetrable - it would take a god to break through Edinburgh's defenses. Cowl would have obtained that much power after performing the Darkhallow.

White Night
In White Night, with the aid of Little Chicago, Harry Dresden follows Grey Cloak to a meeting with Cowl in a miniature hologram-like form (similar to Star Wars). Dresden muses whether Cowl is a member of the so called "Circle", and whether that mysterious organization is actually the Black Council. Cowl senses that Dresden is there eavesdropping and attacks him. Dresden only survives as the attack had to transfer through Grey Cloak's hologram and Little Chicago first, but he is left with a significant head injury.

Later, when Vittorio Malvora is about to lose a duel with Dresden, he calls out "Master!". Cowl enters though a Way, bringing uber-ghouls to the White Court conclave in the Deeps.

Cowl throws(or summons) a flying, fire creature at Dresden and Lara Raith before closing Dresden's gate. Dresden doubts that Cowl was killed in the destruction of the Deeps as he was close to his own gate when the bombs went off.