Regirock is a large golem made of brown rocks. Regirock has an orange pattern on its face that resembles a capital letter "H". It has long arms with jutting shoulders and club-like hands, its legs are short in comparison to its body. There is a line of rocky spines running down its back. When it gets damaged in battle it will search for new rocks to repair itself. Because of this, the rocks it is made of come from several different places, which contributes to Regirock's patchwork appearance. Regirock does not seem to have a heart or brain. It generally lives in caves.
Regirock debuted alongside the other members of its trio in Lucario and the Mystery of Mew. The trio were guardians of the Tree of Beginning, and Regirock was the first of the three to attack Ash and his friends. In the end, Regirock and the other members of its trio realized the group was not a danger and kept on with protecting the Tree of Beginning.
A Regirock made a cameo appearance alongside the other members of its trio in the opening sequence of The Rise of Darkrai, where they all fired Hyper Beams that combined into an extremely powerful one.
A Regirock briefly appeared in PK18, where it sent Meowth and his cronies blasting off after they tried to move it out of their way.
Brandon used Regirock first in his battle with Emerald, where it found Sceptile's Leech Seed attack to be of minor annoyance and knocked it out right away with its Explosion attack. However, while the Pyramid King's attention was focused on Jirachi's light coming from the horizon, Emerald was able to revitalize the fainted Sceptile with a Revive and win the battle.
Regirock is tied with Regice for the highest single base stat of any Legendary Pokémon with its 200 Defense. Regice's is its Special Defense.
In the international versions of Ruby, Sapphire, and Emerald, there is an unobtainable Regirock Doll programmed into the game. It was unlockable with the Japan-exclusive Regi-Dolls Decoration sete-Reader card.
Regirock may be based on the golems of Hebrew legend. The legends cast them as servants of higher powers and are said to have writing on their heads. When the writing is removed, the creature would be weakened, or even killed in some legends.
Regirock is a combination of regis (Latin for royal) and rock.