Moonglow was, in his waking hours, Professor Egbert Whipple—a meek, nervous scholar of small stature at Southeastern University, long the butt of his colleagues’ jokes and burdened by a deep inferiority complex. Humiliated before the faculty when he failed to answer a nonsense question put to him by the visiting prodigy Sylvester Pemberton, Whipple brooded in his cottage near the campus until the light of the moon suggested an idea: that its rays, concentrated upon a human brain, might forge a super-brain. After weeks of labor he built a globular helmet to focus them, donned it beneath a full moon, and emerged a genius, his timidity gone and his name celebrated overnight as the greatest savant of the age. But the moon’s influence soured his temper into violent rages, and when he understood the cause he smashed the globe—too late, for he had absorbed the rays so deeply that moonlight alone now transformed him.

Under that glare his head became a blazing orb of light and his nature turned wholly to crime. Calling himself Moonglow, he fashioned a heatray gun, robbed an armored truck, and woke each morning as the horrified Whipple, vowing in vain that it would not happen again. He murdered the gang boss “Chips” McGurk, seized his mob, and directed a run of brilliant, profitable robberies; when the Star-Spangled Kid and Stripesy ran down his men and wrung from them the location of his headquarters, Moonglow bested the pair and pitched them from a high window, and they survived only by a desperate leap into the river below. Tormented still, Whipple at last telephoned Sylvester Pemberton to confess Moonglow’s identity and beg his help—but the beams reached him mid-sentence, and the line went dead. Twice more drifting clouds spared Sylvester from murder, the glow fading to leave only the bewildered professor; and when at last the heroes saw Whipple transform before their eyes, they knew their man, felled him with an acrobatic twist, and delivered him to the police, who learned to keep him harmless simply by drawing the shades against the moonlight (Star-Spangled Comics #5).

Whatever confinement followed did not hold. By that summer Moonglow was abroad once more, counted among the underworld leaders—with Dr. Weerd and the Needle—marked for death by a hidden killer who slew crime bosses to the chapters of a serialized novel; the three banded together and drew lots, but were caught looting a perfume works, and Moonglow was given over to the police along with his fellows and the killer (Star-Spangled Comics #9). 

Any later criminal activity by Moonglow has not been recorded.