The “Firefly” actor’s Green Lantern will first appear in James Gunn’s “Superman” this summer and then join the series.

He was expected to appear in the series, but now we have the official word: Nathan Fillion will appear in the upcoming "Lanterns" series on HBO. The star of "The Rookie" will play Guy Gardner, a member of the Green Lantern Corp whose live-action role Fillion will debut this July in "Superman.

Nathan Fillion is set to reprise the role of Guy Gardner in HBO's upcoming drama series based on the Green Lantern DC comic. Deadline has been tracking the casting since October. He joins the previously announced cast: Kyle Chandler,