When he first enters McAnally's Pub, he appears like a giant rag ball similar to what is used in a carwash, only spherical in shape as it rolls, creating havoc. Standing, he appears to be humanoid in shape -- tall, lanky and covered in a garment made of strips of rags. Sharkface is hairless and without eyes, only smooth skin where they once were. He has pearly skin with stripes, like that on a shark which is where Harry Dresden’s nickname for it comes from. Its mouth gapes open minus teeth with only a bone ridge where they would be on a human. Its lips are black and black drool drips down to its chin.
The rag strips on his cloak can defect bullets and grab to surfaces. They can even separate off the main garment and seemingly of their own volition, pick up objects and throw them with superhuman force. He Who Walks Before knows McAnally as "Watcher", and McAnally knows of it as "only the first."
Harry Dresden describes the Walker as "not bigger than Mab, but horribly, unbearably deeper than her." Sharkface is capable of launching a psychic attack felt as an intense wave of despair. It can sense the world without its missing eyes and can split into multiple identical shapes, all independently fighting.
He is the general of the Outsiders on the barges, in Cold Days. In this book, he leads a plot to free the monsters—Naagloshii and the Dark Gods—imprisoned underneath Demonreach, while blowing up the island and half the Midwest.
In the series
In Cold Days, He Who Walks Before creates a strange mist outside McAnally's Pub before demanding that Harry Dresden surrender himself. When Dresden refuses to come outside of Unseelie Accords Neutral Territory, it attacks, going up against Dresden, McAnally and Thomas Raith. Dresden attempts to antagonize the Walker but McAnally speaks up, saying "Harry. Don’t Chat. Kill it.". This comment enrages Sharkface, who recognizes Mac, calls him watcher and says he has no place in this. It then says …this gesture…is every bit as empty as you. You chose your road long ago. Have the grace to lie down and die beside it. McAnally then tells Dresden that the creature is only the first. It uses a psychic attack of despair against the three, however Dresden breaks free and retaliates, causing Sharkface to flee.
As Dresden is leaving the pub, Mac stops Dresden and indicates that there are three Outsiders like He Who Walks Before.
Off the shores of Demonreach, Dresden and the Wild Hunt attempt to foil Sharkface’s attack on the island. When the barge Sharkface was standing on is sunk, it shoots out of the water and levels a massive psychic attack against the meddlers. Dresden turns the attack against Sharkface and demands to know its Name, asking three times. Sharkface responds saying "I am Gatebreaker, Harbinger! I am Feargiver, Hopeslayer! I am He-Who-Walks-Before!"
After Dresden disables all the barges, Sharkface commands some of his forces to push one toward the island. Dresden combats the barge with a massive iceberg, but Sharkface comes at him, morphing into dozens of identical copies and carving up the ice. Sharkface then confronts Dresden on the shoreline and tries to recruit him. Just as Dresden prepares to defend himself, the Water Beetle rams the barge, and Raith and Mouse start destroying the ritual onboard. Dresden jams his rifle into the Walker’s mouth and shoots it, adding energy through the barrel of the Winchester. Sharkface's skull explodes into black ichor while his cloak of rags throws his body into the lake. A black cloud escapes his body with a scream and the body and the rag cloak go limp in the icy water.