Darius Dun (sometimes spelled Dunn) is the uncle and guardian of Cody Jones, and after the death of his parents, his only living relative, who served as the C.E.O. of O'Neil Tech in Fast Forward. Since Cody was still too young to run O'Neil Tech, Darius had been appointed chairman of the company until Cody would finally be old enough to take over management.
He serves as one the two main antagonists of the season (other being Sh'Okanabo).
Darius Dunn first appeared the second episode of TMNT: Fast Forward, Obsolete when he came to Cody's penthouse after he was told by Constable Biggles about how Cody was outside the penthouse the day before. He lectures Cody about how he must stay in the penthouse, claiming that it is for his own protection, as their are people who will hurt since he is to the O'Neil Tech fortune, which is supported by Sterling, Cody's robotic butler and caretaker.
However, due to the TV show's cancelation, it's unknown what happened to Darius. It's possible that he got arrested for his crimes.