In the advance description of the upcoming March 21 episode of Supergirl, two new characters are listed that are classic characters from the DC and, specifically, Supergirl mythos.
Warehouse 13 alum Eddie McClintock is listed as playing Colonel James Harper. In DC Comics lore, James Harper is the original Guardian. Created by Joe Simon and Jack Kirby just one year after the debut of Marvel's Captain America, the Guardian brandished a shield as well but was a police officer operating in a city area dubbed Suicide Slum. Kirby later revived the character, with a cloned Harper working as the Golden Guardian for Cadmus. The Guardian was alsofeatured prominently in the Young Justice cartoon.
Meanwhile, Zayne Emory (Crazy Stupid Love) is listed as playing Rick Malverne. Although neither a superhero or supervillain, the Otto Binder-created Dick Malverne is a childhood friend of the original Supergirl, Linda Lee, and dated her later on in life. The character was re-introuced in the late 1990s, this time dating Kara.
These two characters are listed as debuting in the March 21 "Manhunter" episode of Supergirl on CBS.