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. 

Via a variation of the Stand Scary Monsters acquired from Dr. Ferdinand, Diego possesses the ability to transform himself and others into dinosaurs.

Diego is a young man of below-average height and slim to medium build. He has light hair, dark eyebrows, and light, sharp eyes.

During his childhood, Diego was a good-natured and resourceful kid.[6] His mother raised him with love and taught him to keep his dignity in even the direst situation. At age five, witnessing his mother sacrificing her hands so that he could be fed, Diego developed a resentment of everyone around him for allowing that to happen, and an insatiable ambition.[7]

Since then Diego has been driven to climb the social ladder in order to get back at everyone who wronged him in the past. Upon hearing about the Corpse, he first sought them for himself and as soon as he found himself in a disadvantageous position with a crippled horse, didn't waste time in proposing his services to Funny Valentine, demanding mayorship of Manhattan in exchange for his participation.[8] He harbors a grudge against his biological father Dario, and was ready to cooperate with Hot Pants when she proposed to tell him about his whereabouts.[9]

Using any opportunity, he is said to have married an old woman for her wealth,[10] and in the same vein, participated in the Steel Ball Run for prestige. Diego is particularly vindictive against anyone who gets in his way, and doesn't hesitate to injure or kill them, although he doesn't manifest murderous intents automatically. For instance, at one point during the race he warns Gyro to stay away from him as the latter tried to attack him.[11]

Diego possesses a strong misanthropy, describing humanity as a "flock of pigeons", and resents humans as a whole for the death of his mother.[12] Thus Diego is naturally solitary, never looking to bond with anyone, and in case he has to cooperate with someone, he will keep a certain amount of separation between them. Diego sees human life as worthless and will sacrifice anyone to further his goals without hesitation. For instance, he allowed Wekapipo to be killed by D4C's ability in order to escape from a flag.