Rocky is the Amalgam version of DC's Rocky Davis and Marvel's Thing.
Rocky is a United States senator. He accompanied Reed 'Prof' Richards and Sue 'Ace' Storm on a experimental space flight. The rocked was sabotaged and crashed to Earth. Miraculously, they all survived and came to be known as the Challengers of the Fantastic.
In battle with Galactiac
, Rocky was attacked by the nearly omnipotent being and transformed into the Four Armed-Thing and turned on his friends. After Galactiac's defeat, Rocky asked Prof to find a way for him to transform back into the creature.