Steely Dan

Steely Dan (スティーリー・ダン Sutīrī Dan) is an enemy stand user from Part III: Stardust Crusaders.

Personality
Steely Dan is sadistic and arrogant, believing that his stand will prevent Jotaro from harming him and using it to exploit Jotaro in a multitude of ways. His arrogance shows when he pays a child to hit him with a broomstick, but when hit twice, he reacts angrily and punches the child. When his stand is defeated and he is left defenseless, Steely Dan cowers away and attempts to suck up to Jotaro instead, even offering to give him all the money that Dio Brando paid him for the job.

Stardust Crusaders
Steely Dan confronts Jotaro Kujo and his friends in Pakistan. He first executes Enya Geil to silence her, earning the rage of the four men at the time. Regardless, Steely Dan remains calm, mocking Jotaro by saying that he would not be able to touch him. However, Steely Dan is punched in the gut by Jotaro anyway, at which point Joseph Joestar also flies back. Steely Dan takes the opportunity to explain the abilities of his stand and pays a child to hit his leg with a broomstick to prove his point.

Steely Dan announces that he will kill Joseph if he is physically assaulted once more. This enables him to force Jotaro to obey his whim, and he punches Jotaro and hits him with a rock. Subsequently, he forces Jotaro to follow him and involves him in a number of actions at his expense, taking his money, forcing him to use his body as a bridge for him to cross the ditch, and wiping his shoes, among other actions. It is around this point that Steely Dan realizes that Polnareff and Kakyoin have shrunk their stands to combat his. However, shortly after Steely Dan steals a rich bracelet and forces Jotaro to take the blame, he finds his head injured thanks to Hierophant Green's attacks, and is forced to remove his stand from Joseph's brain.

Upon realizing this, Steely Dan attempts to run away, but is abruptly stopped by Jotaro. Steely Dan then tries to buy time by sucking up to Jotaro and attempts to have his stand enter Jotaro's ear. However, Jotaro stops The Lovers with Star Platinum's precision, and subsequently uses it to crush his arm and leg. After The Lovers is released, however, Steely Dan attempts to force it to enter the ear of a young girl nearby, but is rendered immobile due to Kakyoin using Hierophant Green to tie up his stand and prevent it entering anyone else. Shortly after, Steely Dan is subjected to an extended Star Platinum barrage and thrown against a building.

JoJo's Bizarre Adventure: Heritage for the Future
Steely Dan (Written as "S-Terry Dan" in the localised PSX port") is an enemy in the PSX port's Super Story Mode. His chapter features a special minigame set inside Joseph Joestar's head, where the player controls both Hierophant Green and Silver Chariot and attempt to destroy Lovers. The minigame plays like a side scrolling shooter similar to R-Type.

After said minigame is beaten, Steely Dan is punished by Jotaro in a cutscene afterward.

Trivia

 * In the official American release of the manga by Viz Media, Steely Dan's name was changed to "Rubber Soul" for copyright reasons. Of note is that Steely Dan actually behaves similarly to Rubber Soul, as they both believe their stands are invincible, but when beaten, beg for mercy while stating their injuries. Both also attempt to attack Jotaro after being spared and are only beaten further.
 * Being one of the most cowardly and treacherous enemies the Joestar group faces, he suffers quite possibly the longest beatdown by Star Platinum in the entire series: three and a half pages.