Who's This? The old school SF hero on page 29 of Who's Who vol.XXIV.
How you could have heard of him: You might remember Legionnaires Annual #3, part of 1996's Legends of a Dead Earth, in which a time-traveling X-S meets a revamped Gary Concord who is inspired by the Legion to create his own super-team on planet Almeer-5. He's the one who speaks exclusively in clichés.
Example story: All-American Comics #11 (1940) by Jon L Blummer (as Don Shelby)
What do you mean this was never an official part of the DC Universe's future history?
Who's Next? Should we do that JLA villain no one remembers, or should we jump to volume XXV?