Professor Screweyes (voiced by the late Kenneth Mars) is the main antagonist of Jaden's Adventures of We're Back: A Dinosaur Story. He is Captain Neweyes' brother, but is the complete opposite of him. Screweyes is the leader of his own fright circus, and enjoys scaring people. He has his own radio which allows him to find out what people are most afraid of. He also has Brain Drain, which takes away anyone's intelligence. When Louie and Cecilia signed up to join his circus, Rex, Dweb, Elsa, and Woog agree to take the Brain Drain in exchange for the kids to be free. Screweyes used the dinosaurs for his show, but he lost control of them. But they were stopped by Louie and Jaden who pleaded for their true nature, and they got their intelligence back. In the end, Screweyes is devoured by the crows.
- Professor Screweyes will become Jeffrey's enemy in Jeffrey & Friends' Adventures of We're Back! A Dinosaur's Story.
- Professor Screweyes will return in Patch's Nightmares Part 1.