A rift generator is a machine that can create rifts. Lawrence Gordon built one in the mid 1990s and used it to create a rift. After he stepped through the rift, that sent him to Mongo, the rift generator was destroyed.
Several years later, Rankol (with the reluctant help of his prisoner Dr. Gordon) was able to create another rift generator. It was powered by zerilium, a deadly power source. Rankol and Ming used the generator in Template:101 to send a robot to Earth to find the Imex.