Kruppen Feller (クルッペンフェラー Kuruppenferā) was a member of the Aryan Socialist Union, a United States neo-Nazi group, and a subordinate of the group's leader Rachmann.

Feller was a young Caucasian man with a shaven head, a skinny build, and pale skin. He wore a tan military uniform and a red armband of the ASU's symbol.

When the Aryan Socialist Union's ship arrived to the sunken U-boat location to retrieve the painting "The Twelve Knights Led by Brunhilda" for their political party, Rachmann chose Feller as the leader of the descent team to enter the U-boat. Shaking Rachmann's hand, Feller shed tears of joy and claimed that it was an honor to "sacrifice" himself for their group. Just before the diving pod slowly submerged below the ocean surface, Feller gave a Hitler salute before closing the pod's hatch. When his diving team loudly entered the sunken boat, Revy started shooting at them once determining their numbers, so they returned fire. In the firefight, Rock accidentally allowed the painting to fall to the other side, allowing Feller to steal the painting. Once returning to the diving pod, Feller ordered Streicher to quickly ascend, not even slightly concerned about the fate of the other neo-Nazis in the U-boat. As they descended upward, Feller saw blood outside the window, prompting him to warn the ASU members above to shoot the enemy "grave robbers" when they emerged from the water. When the two pirates appeared to have been defeated, Feller bragged about their victory.

That night, Feller and the group celebrated their victory on their ship by drinking beer and listening to classical German music. When Revy and Dutch began their raid on the boat and started killing the neo-Nazis onboard, Feller panicked and quickly went to the armory to retrieve a machine gun, but before he could properly load the gun, Revy was behind him and he felt her eyes staring at him. He quickly pulled out some grenades but Revy shot him first, and the live grenades exploded in the armory with Feller inside.