On Earth-A,
Cosmic Custodian is an identity shared by many titans (i.e.
superheroes) over the years. They are also members of a pan-galactic law
enforcement organization, The Cosmic Custodians.


The first Cosmic Custodian was the second titan (i.e. superhero)
of Earth-A and emerged in 1914, a few months before the Great War. An
Irish-descended immigrant, Jeremy O'Brien was a farmhand. One night, a
sphere of blue light descended from the sky. A voice came forth from the
miniature star, stating that he been chosen as a test subject for the
"Cosmic Custodian project". The voice asked him if he would like to
volunteer for this project. Jeremy agreed. The sphere separated into two
pieces, wrapped around his wrists, and solidified into bands of blue
metal. Cosmic Custodian and the other titans helped to end the war in
1917 and to indirectly prevent the rise of the Nazi party. He along with
the other titans helped fight in the Second Great War, but did not
survive.


The sixth (current) is David O'Brien, descendant of Jeremy
O'Brien. He possibly developed his unusual features (hairlessness &
glowing blue eyes) from his family's constant exposure to radiation from
the Cosmic Custodian's "power bands".

from PDSH's description

Credit to The Multiversity for the template