First Appearance: All-Winners Comics #6 (Fall 1942).
Golden Age Appearance: All-Winners #6.
Modern Appearance: None.
Dates Active: 1942-?
As far as I know this character was a generic Golden Age hero with no powers and nothing out of the ordinary to recommend him. I haven't read the issue in question and am relying on others' testimony for what's here.
Note: Jim Steranko, in volume 1 of his History of Comics, says that the Thunderer become the Black Avenger. Unfortunately for Mr. Steranko, there's nothing in All-Winners #6 to prove this, the character making no reference to having been the Thunderer or being identified as the Thunderer. My guess is that the Black Avenger story in All-Winners #6 was simply a Thunderer inventory story slightly redone, which is probably what happened with the Blue Blade and the Fourth Musketeer. Still, as with those two worthies, the text of the stories themselves portray the Thunderer and the Black Avenger as being two different characters, and so I'm counting them that way.