Wikipedia
Blockführer (Block Leader) was a paramilitary title of the SS, specific to the Totenkopfverbande (Concentration Camp Service). An SS-Blockführer was typically in charge of a prisoner barracks ranging from two hundred to three hundred concentration camp prisoners; in larger camps, this number could be as a high as 1000. The Blockführer was in charge of daily attendance, supervising daily work details, and distributing rations to prisoners. Assisting in this case were several prisoner trustees, known as Kapos. The position of Blockführer was usually held by an SS-soldier holding the rank of Unterscharführer or non-commissioned officer rank of '' Scharführer.
In the Nazi death camps, the task of gassing prisoners with Zyklon B was performed by a Blockführer. A similar title, known as Blockleiter, also existed as a Nazi Party political rank.