Professor Milo, full name; Professor Achilles Milo, is a villain in the DC Universe and an enemy towards Batman.
Little is known about Milo's past. All is known is that he was once a renowned chemist until he fell from grace for unknown reasons. Since then, Professor Milo has turned to a life of crime and has been a long-time foe of the Batman.
DC Animated Series
Professor Milo was one of the villain Batman encountered in the TV show; Batman; The Animated Series. He sometimes works for Roland Daggett, on more than one occasion. He, along with Daggett were also were planning to distribute a virus inside stray animals so they can sell the antidote and make millions. But Batman managed to find evidence on what they were planning and successfully arrest Milo. Professor Milo was the one responsible for turning Anthony Romulus into a living werewolf. He told Romulus that he has the cure, but instead of giving him the cure, Milo decided to blackmail him, and force Romulus to do whatever he asked him to do. However, Milo ended up getting hospitalized when Romulus was changing into a werewolf. The cops managed to arrest him, but Milo pointed out that there's no evidence, to which Gordon replied; "Don't bet on it."
Later on, Milo was recruited by Amanda Waller to be a member of Project Cadmus. However, Milo was demoted to a lower position after a failed warthog experiment in his research of Dr. Kirk Langstrom, the former Man-Bat. Seeking revenge, Milo released Doomsday to kill Waller. After Waller found out, she was personally going to kill Milo, but a guard told her that Doomsday already beat her to the punch, indicating that Professor Milo is dead.
In other media
Professor Milo appeared as a flashback antagonist in the 2018 crossover film, Scooby-Doo! & Batman: The Brave and the Bold.