These enormous soliders were developed by the Robotech Masters to work as their primary military force. Besides their size, the Zentraedi were genetically engineered to withstand the vacuum of space and relatively severe injuries.
Cloning technology of the Robotech Masters also made the Zentraedi warriors expendable, and also served to keep the Zentraedi from the distractions of propagation. In the interest of turning the Zentraedi into the perfect soldiers, societal control was taken to an extreme, forbidding personal interaction between males and females.
During the First Robotech War, the Zentraedi were reintroduced to many of the cultural elements they were denied. After the defeat of Dolza's Fortress and the Zentraedi armada, most of the Zentraedi who were allied with the humans underwent micronization and were integrated into human society.