Vance Cosmic is the amalgam of Cosmic Boy and Vance Astro.
Vance Cosmic is a member of the Sinister Society and is composed of Inerton, a super tough metallic substance. He was sent along with his comrades in an attempt to capture the Magnetic Men in order to learn their secrets in order to become human again.
The Society was defeated though, but soon joined forces with the Magnetic Men because of their shared enemy, Will Magnus.
The older Vance Cosmic is from Earth-12772 and the younger has counterparts on Earth-97061 and Earth-9602