Presented for your delectation: some very minor super-heroes.

Mantor the Magician:

Mantor the Magician is a magic-using hero in the classic mold. He has a single Golden Age appearance in which he helps a damsel in distress, gets knocked out once and foils a plot by some fake ghosts. Years later (about two years ago as I write this) he is brought back and killed off as an easy way to raise the stakes on a super-threat. It’s all so depressingly familiar. He does however have a fun magician’s outfit, so that’s something. (Human Torch v1 002, 1940)

Miss America **UPDATE**:

After fighting crime for three issues in the same fairly distinctive dress that she wears for work, Miss America finally gets a proper, albeit maskless, costume in Military Comics 004, 1941. As with so many Golden Age costumes the design is never finalize, and Miss America has a slightly different look in Military Comics 005, as well as in both of her 1942 appearances.

Dash Dixon **Update**:

Speaking of costumes, Dash Dixon has always been a troubling figure to me, due to the fact that in order to maintain his vast physical power and immortal nature he must wear a very sub-par outfit (that includes, don’t forget, a hair-shaped helmet) forever. In this, his final appearance, we learn that there is hope for Dash as the power is seen to dissipate eventually despite the suit and requires occasional top-ups. This means that – at least theoretically – Dash can occasionally not look like a huge dork. Wotta relief. (Miracle Comics 004, 1941) 

the Masked Ranger:

The Masked Ranger is a standard unit of Old West masked cowboy hero, complete with the requisite horse (Star) and sidekick (Pedro). He adventured for just a handful of issues, and has not yet been brought back to be killed off as an easy way to raise the stakes on a super-threat. (More Fun Comics 036, 1938)