Large and bulky, Knifehead is a heavily built Kaiju. Its most notable feature is the long and broad sharp-ended nose, that could easily cut through the armor of a Jaeger. It has a large shell-like armor on its back, while the rest of its body is similar to a goblin shark in appearance.
Knifehead's two large dominant arms and two smaller secondary arms protrude from its belly. Its large arms each have three clawed digits, the middle digit being significantly larger. Bright yellow lines run through a pattern across its body, with the rest of its body being a dark grey. Its eyes and the interior of its mouth, however, glow blue.
Like Slattern and Scunner, Knifehead's primary arms are actually two fused arms themselves ending in three-digited claws.
Knifehead is the largest Category III Kaiju recorded so far, deployed to attack Anchorage, Alaska. On its way to its target, Knifehead moves to attack a fishing boat, but is intercepted by Gipsy Danger. The Jaeger manages to grab and toss the boat out the line of combat. Knifehead attacks Gipsy, but only succeeds in biting at its arm, before being given a severe beating. It takes three shots from Gipsy's Plasmacaster which sent it hurling back into the ocean.
Gipsy Danger's pilots, Yancy and Raleigh Becket, assume Knifehead is dead and let their guard down. Knifehead ambushes them, attacking them from under the sea and tries to bite the Conn-Pod. Raleigh tries to charge Gipsy's left Plasmacaster, but Knifehead grabs Gipsy's arm so he is unable get a shot at it. Knifehead rams the sharp end of its head into Gipsy's left shoulder. It severs the Jaeger's arm and proceeds to rip and tear at Gipsy's severed shoulder using its teeth.
Knifehead tears open the Conn-Pod, and rips Yancy out of the cockpit, hurling him to his death, leaving his brother Raleigh to pilot what remained of Gipsy solo. Knifehead strikes Gipsy with its head and impales Gipsy's left breastplate while it continued to bite at its severed shoulder. However, in its frenzy, it stopped gripping Gipsy's right arm. Raleigh charges the plasma caster and unloads a clip into Knifehead's face, killing it.
Scunner and Knifehead use the same basic CG body as Trespasser in Pacific Rim.
In a preview of Pacific Rim: Tales From Year Zero, Knifehead's skull can be clearly seen mounted on the room, and in the next page Gipsy Danger's damaged body.
Several identical copies of Knifehead can be seen in the Precursors processing facility (hundreds in concept art of the film). This hints at the idea that there were to be many attacks from this Kaiju type.
Knifehead appears in Pacific Rim: The Video Game.
Knifehead bears a resemblance to Guiron, a similar monster from the Kadokawa Daiei Gamera series.