Gim Allon is Colossal Boy's real name. While vacationing on
Mars, he was exposed to the
radiation of a strange
meteor, giving him the
ability to grow to enormous size.
The largest size recorded that Colossal Boy has grown in 4000 feet, but he generally grows to 60 feet. He also has
super strength.
Colossal Boy joined the Legion at the same time as Reep Daggle, dubbing him with the name
Chameleon Boy.
Colossal Boy was romantically involved with Shrinking Violet. Their relationship was
shattered when Violet was kidnapped and held hostage, while her
place was taken by a Durlan. Gim and the Durlan fell in love and were married.