The Kaiju Eugenicists (怪獣優生思想 Kaijū Yūsei Shisō) are a team of four Kaiju Users, who are the main antagonists of SSSS.DYNAZENON. They control Kaiju using an ability known as Instance Domination.
5000 years ago, the Kaiju Eugenicists, with Gauma being one of them, brought fortune to a certain country through the use of their power to control Kaiju. They were known as "dragon controllers" to the neighboring country. The princess of their country became interested in the power, but then the Kaiju Eugenicists were betrayed by the country, while also betraying the country themselves. Gauma, having shifted his loyalty to the princess over his comrades, killed them and then fell over, and seemingly died, gaining the scars on his face in the process.
5000 years later, Gauma and the Kaiju Eugenicists were revived in the modern day. Gauma had betrayed them and pilots Dynazenon to fight against the Kaiju they control. They reappeared some time later, being the cause of the Kaiju attacks by Shalbandes and Greyjhom. After the latter was defeated, they revealed their presence to Gauma and the other Dynazenon pilots.
After Garnix's defeat, the Kaiju Eugenicists believe they have lost as all the Kaiju seeds have been wiped out. They start to leave to do their own thing, but Sizumu unleashed Gagula from within him. Gagula devours the other three Kaiju Eugenicists to change into its second form, but they are defeated nonetheless. This time, they are killed for good by Dynarex and Gridknight.