When DC's Legends of Tomorrow brings the Justice Society of America to life on the show, they'll be bringing in veteran actor of movies, TV, and voicover Lance Henricksen in as Obsidian. It'll be a very different take on the character, who has the ability to manipulate dark energy.
In the pages of DC Comics, Obsidian is typically one of the younger members of the team, the son of the original Green Lantern Alan Scott. Casting an older actor could indicate that they'll only be meeting Obsidian in the present-day or even the future, as producers have already confirmed that the JSA will be a WWII era team of heroes. Thanks to the time travel aspect of the show, it's very possible we'll meet the JSA several times, each time with different lineups.
Henricksen's legacy in action and genre entertainment is impossible to challenge. He's been Lockdown in Transformers more than once, done voices in Call of Duty and Mass Effect games, voices on TRON: Uprising and The Legend of Korra, and oh yeah, he was Bishop in Aliens, the first modern interpretation of an android with a personality (and maybe even soul) of his own that has been a Sci-Fi standard since.
Legends of Tomorrow season 2 kicks off the first week of October in the same Thursday 8pm timeslot.