Rayearth

Rayearth is a Rune God and one of the three legendary guardians of Cephiro. Rayearth is in fact an ancient mecha used by the Magic Knights to help them combat Zagato and ultimately kill the Pillar. Rayearth is paired with Hikaru Shidou. In the OVA series, Rayearth is a lion and renamed Lexus. (Source: Magic Knight Rayearth Wiki)