Emperor Crisis (クライシス皇帝, Kuraishisu Kōtei), also known as Grand Lord Crisis, is the ruler of the Crisis Empire, who is not seen at first but mentioned several times throughout the series. He resides in Crisis City at the Empire's home world. He is the primary antagonist of Kamen Rider Black RX.
He conquered the Demon World in the distant past, transforming it from a peaceful world into an industrialized universal power which expanded its claws onto multiple planets. However, due to the Emperor's policies, completely disregarding the nature of the Demon World, its environment was destroyed and the planet itself was slowly dying, heading to complete destruction.
Aiming to save his empire, Crisis sent his army to take over Earth, planning to destroy humanity and move the population of Crisis from their original world to rule Earth. To inspect the invasion's lack of progress, he eventually takes charge of the operation disguised as Dasmader, a high ranking inspector supposedly sent by the emperor himself.
After many failures, Lord Crisis eventually offered Black RX the chance to replace General Jark and become the new right hand or even rule Earth if he agreed to his plans. When refused, he faced Black RX as Dasmader, attempting to destroy Black RX with the Crisis Fortress, only for RX to follow him into it.
Black RX finally sees Crisis itself from space, and realizes that it's identical to Earth. In fact, the Emperor claims that Crisis is a mirror world to Earth, and it's dying due to Earth's pollution and humanity's evil, only for Black RX to reject his claims, affirming that it was the Emperor's policies that led to that.
After being defeated as Dasmader, he revealed himself, appearing as a giant alien head in a last attempt to defeat Black RX. He was destroyed by RX's Revolcane, dying alongside his world, while claiming that as long as humanity's evil continued to exist, they'd give birth to a new Crisis and he'd return alongside it.