The Comet is a fictional character that first appeared in Pep Comics #1 in January 1940. Possibly the first superhero killed in the line of duty, he died in issue #17 (July 1941), which also introduced his brother, a brutal hero called the Hangman.
In Pep #1, in a story drawn by Jack Cole, young scientist John Dickering has discovered a gas fifty times lighter than hydrogen. By injecting small doses of it into his bloodstream, he is able to make great leaps through the air. After a number of injections, twin beams come from Dickering’s eyes and when he crosses the beams, whatever he is looking at disintegrates. He makes a glass shield (visor) as that is the only thing his beams will not disintegrate, a weakness often used against him from the first story on wards.
In the second story, tied up and unable to raise his visor to save himself, he smashes it against a rock, breaking the glass. Realizing that such a discovery could wreck humanity, Dickering destroys the formula for the gas and uses his powers to benefit humanity.