Superman: Legacy is introducing other DC characters such as Green Lantern, but it's not going to include the Green Lantern that most fans anticipate. Instead, Nathan Fillion plays Guy Gardner, one of the other Green Lanterns who was Hal Jordan's first replacement. Guy's presence instantly establishes legacy beyond Superman, namely that of the Green Lantern Corps and the wider DC Universe.
Source：https://www.cbr.com/guy-gardner-warrior-dcu/
