Diego Brando, commonly referred to as Dio, is the secondary antagonist featured in Steel Ball Run. Diego Brando is a genius British jockey, hailed as one of the best contenders to win the Steel Ball Run race. However, he eventually shifts his attention to gathering the Saint's Corpse for President Funny Valentine instead, after becoming aware of the race's true purpose. Diego becomes a long-standing rival of Gyro Zeppeli and Johnny Joestar throughout the Steel Ball Run, and although he teams up with many different individuals throughout the part, in the end, Diego is only ever truly loyal to himself.

After obtaining the Left Eye of the Corpse while under the control of Dr. Ferdinand's Stand, Scary Monsters, Diego acquires his own independent version of the same Stand which remained after Dr. Ferdinand's own death. Diego first turned into a dinosaur after he, along with a number of villagers, were controlled by Dr. Ferdinand in order to steal the left eye of the Saint's Corpse from Johnny and Gyro.