The Lords are a group of powerful disciples serving under the OverLord, who created them from his body. Referred by the police department as Unknown (アンノウン, Annōn?), to differ them from the Unidentified Lifeforms (Grongi Tribe) that attacked humanity two years ago. In fact, according to books and mini-encyclopedias about Kamen Rider Agito, the Lords are actually related to the Linto (リント, Rinto?) tribe, defending them from the Grongi in the past, thus linking the Lords to the Linto as humanity's protectors. This war between the Grongi and Unknown is further explained in Kamen Rider Decade.
The OverLord (オーヴァーロード, Ōbārōdo?) is the highest power among the Unknown, and is referred to as the creator of the human race. Long ago, there existed twin entities of the Linto Tribe; one being the embodiment of light while the other was embodiment of darkness. These twin 'brothers' co-existed in harmony for a time, eventually creating our world. However, neither could agree on who would reign over their creation and a battle for control took place. In the end, the Overlord of Darkness triumphed over his brother, the Overlord of Light. But with his dying breath, the Overlord of Light bestowed his essence upon humanity--the power of Agito--with the hopes that, one day, they would evolve beyond his control. But the Overlord of Darkness refused to let this occur, taking it upon himself to personally eliminate the vessels of Agito, creating the Lords to kill all humans who possess the potential to "evolve" into Agito.