Jerom originates from the prehistoric times. As a child, he was very weak and pale. His mother contacted a shaman, who asked her to drew Jerom as she liked him to see. The shaman blew magical dust through a bone on the cave drawing, giving Jerom his strength. But soon a flood, swept Jerom away and he got somehow frozen in a block of ice until he's found in 17th century by Duke Le Handru. He uses Jerom as his own personal army, but Suske and Wiske managed to convert him. Since then he's brought back to our time and lives with Lambik.
Sometimes he has solo adventures or as part of the Morotari, a modern-day knights of the round table.
Jerom made his first appearance in the comic book Suske & Wiske in 1953. He was created by writer and artist Willy Vandersteen who gained the title of spiritual father to Suske & Wiske. In 1962 he got his own spin off comic book Jerom.
Jerom used to be written and drawn like a dumb caveman wearing nothing more than a bear pelt. But in that time this was considered an outrage and over time he was drawn in normal everyday clothing and was acting more civilized. He turned out to be one of the most popular characters of the comic book and as such even got his own spin off comic. However, due to his tremendous powers he was often viewed as a deus ex machina or plot device because he could handle most situations by his own.
Jerom has tremendous strength, the limits of his strength are not known but it is well over a 100 tons. He's also invulnerable, being able to survive explosions with no damage to his body or have bullets bounce harmlessly of his chest. In many ways his powers are similar to Golden Age Superman. With powers like using his breath as a gust of wind or even freezing. He has super speed easily able to catch bullets and ran at and incredible pace. He's able to leap like the Hulk.
His mother Mie once appeared to him when Jerom blew on the same bone with magical dust that gave him his strength. She told him about his youth and that his father had died in the war against the rivaling race called Grotkastaars.