Mark Horley was a criminologist whose great intellect drove him to crime to satisfy his ego. In his lab, he created a formula which changed him in a Dr. Jekyll and Mr. Hyde fashion. By night, he was a hideous Monster terrorizing the streets. By day, he was working with the police investigating his own crimes. The Black Hood caught on to Mark's dual lifestyle and when confronted, the Monster took poison capsules and died.

*Top-Notch Comics #20

*[http://www.comics.org/issue/1673/ GCD]
Category:MLJ Characters
Category:Comic Book Characters
Category:Harry Shorten - Creator
Category:Warren King - Creator
Category:Male Characters
Category:Villains
Category:Monster Characters
Category:1941 Debuts
Category:Dead Characters
Category:Shape-Shifting Characters

Monster

Mark Horley was a criminologist whose great intellect drove him to crime to satisfy his ego. In his lab, he created a formula which changed him in a Dr. Jekyll and Mr. Hyde fashion. By night, he was a hideous Monster terrorizing the streets. By day, he was working with the police investigating his own crimes. The Black Hood caught on to Mark's dual lifestyle and when confronted, the Monster took poison capsules and died.

All data from the awesome folks at Marvel.