Matt Nable will be reprising his role as Ra's Al Ghul for the Arrow/Flash spin-off, DC's Legends of Tomorrow. It's unclear whether Nable will have survived his season 3 finale battle with the Arrow or if Nable's appearance will be through Legends of Tomorrow's time-travel adventures. Current Arrow baddie, Damien Darhk is also confirmed to appear on Legends of Tomorrow so perhaps we'll be traveling back in time to a period when Darhk was still a member of the League of Assassins?
Ra's implied in season 3 of Arrow that he's at least a few centuries old thanks to the regenerative powers of the Lazarus Pit. However, Malcolm Merlyn, the new Ra's, stated during this season's crossover episode that the League of Assassin's has no intel on Vandal Savage which would indicate that Savage and the League have never crossed paths during their long lifespans. Without knowing what Savage's agenda will be in Legends of Tomorrow it's hard to predict how the interaction between Ra's and Savage will come about.
If you have your own theories, take it to the comment section below and keep the conversation going.
DC's Legends of Tomorrow premieres January 21st at 8/7c on The CW.