The cyborg known only as Lion Man (ライオン男 Raion otoko) is part of the Mythos team developed by Dr. Gaia and Dr. Uranus, and appears in the Mythos arc in the manga.
Along with the rest of his team, he is used to challenge the 00 cyborgs and wipe them out for their betrayal of Black Ghost.
True to his name, Lion Man is a hybrid of a lion and a man, being bipedal and humanoid but with a lion's face and mane. He wears golden arm and wrist bands, a Greek tunic and cloak, and gold gladiator sandals.
A 1970s color illustration by Ishinomori depicts Lion Man is having a pale green tunic, as well as orange fur and body with a white "beard", and glowing red eyes.
Lion Man, like the rest of his team, is fiercely loyal to his creators, though he sides more with Dr. Uranus' ways at first. He is willing to do whatever he can to ensure victory, and will give his all in battle.
At the start of the arc, he is the first of the cyborgs to raise curiosity over who wiped out the Cyborg Men, believing that he and his group were the strongest and unmatched.
Lion Man has the ability to send shockwaves from his mane, electrocuting and destroying anything that touches him. He can also emit destructive waves from his paws.
As part of the Mythos cyborg team, Lion Man was given orders to challenge the 00 cyborgs to the ultimate battle to defeat them, as well as prove him and his team members to be victorious. He agreed upon Dr. Uranus' conditions of a fair fight, with the 00 cyborgs being made to come to Magma Island to prevent the Mythos team from waging worldwide destruction, and to battle on their own terms there.
During the climax of the conflict on the island, Lion Man faced off against 002, 004, 005, and 006, who found him difficult to attack due to his strength and power. However, as the island began to be destroyed by the natural disasters exacerbated by the Woman Esper and 001 in their telekinetic fight, Lion Man was buried in a rockslide and presumably killed.
- This character was proposed to appear in the 1979-1980 anime series' adaptation of "Mythos", which ultimately went unproduced due to Nippon Sunrise pulling out of the production. In the sketches by Ishinomori (which would be used for Toyoo Ashida to base the designs from), he was given a more expressive face. In the earliest draft for the arc, he was to initially fight 008, but a later draft dropped this detail and had the battle changed to 005 and 008 fighting Poseidon.
- While never given a name by Ishinomori in the actual manga and only identified as "Lion Man" in the notes for the aformentioned anime adaptation (as well as the Shotaro Ishinomori Character Guide), this character was christened as Heracles when he appeared in the 1993 Mega-CD video game adaptation.
- He would also appear in a 2000 visual development trailer for the "Cyborg Soldier" series, designed by Naoyuki Konno. Unfortunately, due to constraints of storyline and to simplify the arc, he was one of the characters that ultimately did not make the cut when the anime went into production. In Konno's design, Lion Man was depicted as having white fur and black eyes.