Diego Brando is a genius British jockey hailed as one of the best contenders in the Steel Ball Run race, but he soon shifts his attention to the Saint's Corpse. Diego becomes a powerful intermittent rival to both Gyro and Johnny. Although he works with different factions during the course of the race, Diego is only loyal to himself. 

Diego is a young man of below-average height and slim to medium build. He has light hair, dark eyebrows, and light, sharp eyes. He commonly wears an equestrian helmet with the letters "DIO" loosely mounted on bending pins emerging from a small ribbon tied at its front, a turtleneck jumper patterned with a diagonal grid, light, mid-forearm-length gloves, jodhpurs with flared hips, and tall, dark riding boots.

After obtaining the Corpse's left eye and fusing it with his own, his left eye's iris has the word "TURBO" engraved on it, and he temporarily gains a mark under said eye reading "DIO", contrasting to the cross Gyro gains from the right eye.