Controllers

The Controllers are a race of immortal aliens that live in another dimension. Despite being generally benevolent, the Controllers are sometimes difficult to deal with, for their perspective is considerably detached to that of other species.

It was eventually revealed that their are related to the other group of immortals, the Guardians of Oa who established the Green Lantern Corps.

The Miracle Machine is a Controller creation.

Clonus

The 1988 Wanderers Series introduced a renegade Controller named Clonus, who lived in the Legion of Super-Heroes dimmension for several human generations. Unlike most other Controllers, Clonus developed an active interest in other species, to the point of marrying a human woman and developing effective cloning and mind transference techniques to extend her life (as revealed in issue #4 of that series).