Terrakion is a bovine, quadrupedal Pokémon. It has a black, rounded forehead adorned with two sharp brown horns that curve forward. Its face is beige with orange eyes and a short snout. On top of its head are several short spikes. Down its back are two brown ridges that join just past its shoulders. There are two orange protrusions on its shoulders. The bands around its legs are the same color as its face, and it has black hooves underneath these bands. Its striped underside is also beige. It has a short, stubby tail.
Terrakion fought humans alongside the other Swords of Justice during a war with humans in order to protect Pokémon. Terrakion is said to possess a phenomenal power, which can destroy a castle wall with one blow. Should a small Pokémon be bullied by anyone or anything, Terrakion will crush them without mercy.
Terrakion is based on the character of Porthos from the novel The Three Musketeers.