Little is known about Mister Obsidian, except that he seems to be impervious to physical attacks. His name wasn't revealed upon his first appearance in volume 3 of The Second Journey of Agatha Heterodyne; in fact, it was not mentioned until he reappeared in the next volume. Furthermore, it is far from certain that Mister Obsidian is his real name; it may be an alias or nickname based on his apparent invulnerability.