Since the helium-cooled pebble bed (HCPB) breeding blanket was accepted as a reference blanket concept for a future DEMO reactor in the European Union almost 10 yr ago, research and development on the breeder unit (BU) has been conducted. As the basic module of the modular blanket segmentation, the BU is the key component to fulfill the prescribed functions of the breeding blanket. In the paper, two design schemes of the HCPB BU are discussed: (a) a design with double breeder beds confined by an m-shaped container and (b) a design with a single breeder bed confined by a simpler n-shaped container. The first design features a stack of parallel straightforward channels in the cooling plates, and the second design features a group of meandering channels. The two BU variants are analyzed numerically with regard to the performance of their neutronics, thermal hydraulics, and structural mechanics. Based on the numerical analyses, the two variants are compared in the three aspects. Finally, possible improvements on the HCPB BU designs are proposed.