Der has what might be the most fitting name in the whole book. It just sounds like the name of some sort of big, hulking, dumb bully. Or an ogre. He's like Shrek's mean cousin or something.
Actually, Der is a mean overseer, so the ogre comparison isn't too far off. Der has one scene in the book, but it's definitely a doozy. After all, he nearly gets beaten up during it. Der decides to confront Tyurin over the stolen tarred paper in the Power Station. Like Fetyukov, Der is a former rich dude (a ministry employee apparently) who tries to throw his weight around, only to discover that he has pretty limited power in the camp:
He was wearing a splendid leather cap. But it had a number on it, like everybody else's, B-731. [...]
"What the hell do you mean by it?" Der was yelling, spittle flying. "You're asking for more than a spell in the hole! This is a criminal offense, Tyurin! You'll get a third term!" [...]
Shukhov had never seen the foreman look so ugly. He threw his trowel down with a clatter. Took a step toward Der. Der looked behind him - there was Pavlo, shovel in the air. [...]
Der blinked and looked around nervously for a bolt-hole. (601-610)
The detail about Der wearing a number just like everyone else is really crucial here. Even though he's in a position of some authority, he's still a zek like everyone else. And in the camps, as we've seen, high social class and money don't always amount to much, especially in the new camp environment where throat cuttings are the norm. Der is a sign of change in the camp: he's the jerk who is suddenly threatened, in a very real way, by the zeks in lower positions. And he also helps to demonstrate just how limited prisoners' power really is, even those in more privileged positions.