Yesterday, "Supergirl" released the episode synopsis for "Manhunter," an upcoming episode detailing the origins of J'onn J'onnzz on Earth, and what happened to Kara's father, Jeremiah Daniels (Dean Cain).
Listed among the guest cast is a pair of characters, who just might have bigger roles to play as "Supergirl" rolls on: Col. James Harper (played by "Warehouse 13" vet Eddie McClintock) and Rick Malverne ("Crazy, Stupid Love" Zayne Emory).
The former is the civilian identity of a classic Jack Kirby and Joe Simon creation, the Guardian. Jim Harper (no Col. designation for the comics incarnation) is a superhero created by Simon and Kirby in 1942; with no super powers, he relied on his athletic prowess and indestructible shield to fight crime, not unlike Captain America, who Simon & Kirby had introduced a year earlier. The original Guardian was a police officer patrolling the streets of Suicide Slum, operating as a superhero in order to tackle criminals he couldn't stop via official channels.
In the '70s, Kirby introduced a clone of the original Jim Harper as part of the cast of "Superman's Pal Jimmy Olsen." This Golden Guardian worked for Cadmus, an organization dedicated to cloning experiments, and home to a number of other Kirby creations which went on to influence the DC Universe in numerous ways. In the '90s, Cadmus used Superman and Lex Luthor's DNA to create a superpowered clone who would become Superboy. A version of this Guardian was introduced to millions of viewers through a recurring role on the "Young Justice" animated series.
The other character, Rick Malverne (created by Otto Binder), is a bit more obscure, but still a vital part of Supergirl's comic book mythos. The original Richard "Dick" Malverne grew up in the same orphanage as Supergirl, and dated her civilian identity, Linda Lee, throughout college. Introduced in 1959, Malverne played much the same role as Lois Lane did to Superman at this time, constantly attempting to prove Linda and Supergirl were one and the same.
A later incarnation of Malverne appeared in the '90s "Supergirl" comic where he was not only a love interest for Kara's civilian identity, he was also possessed by a demon named Buzz, who attempted to kill Supergirl on numerous occasions.
"Supergirl," like its CW counterparts "The Flash" and "Arrow," has a history of not introducing characters with familiar names without a payoff in mind. Most of the time, it's exactly what you think -- a new iteration of a classic character. Sometimes, it's a feint, like Hank Henshaw being revealed as J'onn J'onzz/Martian Manhunter rather than Cyborg Superman. It's extremely rare, however, for a classic name to be used for a 100% unrelated character.