Die Namenlos appear to be secret Nazi agents. These enemies will shoot at the player at a very rapid pace. Combine that with their quick movements and the ability to roll around, you have an extremely deadly adversary.
The ideal way to handle this enemy is to not deal with them. In other words, make sure these guys are high on the priority list when entering a room. If there are more pressing enemies then the best thing to try is strafing around the outside of the room. Their attacks are similar enough to a Gilead's that it should do the trick.
Die namenlos means "the nameless" in german
in earlier versions, namenlos could fly in the air while still making the running animation