Obsidian

Obsidian was a member of the Justice League after the Thanagarian invasion.

Background Information
In the comics, Obsidian is the heroic identity of Todd Rice, the son of the original Green Lantern Alan Scott, twin brother to superheroine Jade, the possessor of "shadow" powers, and homosexual.

The action figure of this character, released by Mattel in the Justice League Unlimited line has confirmed that this is indeed Obsidian.