While The Umbrella Academy season 3 will introduce new protagonists through the Sparrow Academy, it also needs to bring in the comic books' scariest villain. The version of the Umbrella Academy in a different reality was the final reveal from The Umbrella Academy season 2, as the protagonists traveled back to their own time to find that they had been replaced by the Sparrow Academy in this timeline, led by a sinister Ben setting up The Umbrella Academy season 3. The most interesting detail about this revelation is that this team is led by a grown-up Ben Hargreeves, suggesting that it’s a version of the Umbrella Academy that never grew apart. It sets the perfect backdrop to introduce the villain Doctor Terminal, an unstoppable force who can only be stopped with the combined might of the Umbrella Academy and the Sparrow Academy.
Doctor Terminus was introduced in The Umbrella Academy: Apocalypse Suite #3 through a flashback involving younger versions of the protagonists from the show and could only be stopped by Reginald Hargreeves, their adoptive father. He was one of the Umbrella Academy’s more chilling villains from their childhood, originally having been a scientist diagnosed with Eisenstein’s Syndrome. Doctors said it would take two months before the rare disease devoured him from the inside till it destroyed his brain. However, the scientist created a device that converted matter into energy that was used to feed the disease and keep him alive. His grounded yet apocalyptic nature could prove to be the perfect antagonist for the Sparrow Academy to fight in Umbrella Academy season 3.
From what has been revealed about the characters of the Sparrow Academy, it’s clear that the crime-fighting team has lasted a lot longer than the Umbrella Academy did in their timeline. Using Doctor Terminal would help showcase the dark reality of crimefighting, especially since the original timeline never showcased the Umbrella Academy’s greatest battles. One of these battles from the comics involved a time where the villain ate Allison’s arm when she was just a child, shortly before her adopted siblings managed to save her. Although it wouldn’t be possible to incorporate the plotline exactly the same way into The Umbrella Academy season 3, the show could portray Doctor Terminal’s sadistic hunger by incorporating it into one of the Sparrow Academy members’ storylines.
Another reason why Doctor Terminal’s introduction would work so well in Umbrella Academy season 3, aside from him being a motivating factor for the two timeline academies to unite, is the fact that the comic book villain has already been confirmed to have existed in the original timeline. In Harold Jenkins’ flashback scene, he's playing with Umbrella Academy figurines while fighting the “evil Doctor Terminal,” who he mentions by name. While it confirms that the character exists, it's not clear if Terminal is fictional or real since Harold was playing with action figures, which may even end up being a relevant connection since it’s not clear what Harold Jenkins’ role in Umbrella Academy season 3 might be.
Since Umbrella Academy season 3 is set in a timeline where the Sparrow Academy defeated the same villains that the Umbrella Academy would have fought, Doctor Terminal could be a shared foe between the heroes. The major issue that the introduction of Doctor Terminal might face is his aesthetic. The character is admittedly more suited for the campy tone of the comic books. However, The Umbrella Academy has made many changes from the comics, which means that it could deliver on a more grounded version of the villain that's even scarier than the comics.
Ultimately, the introduction of the Sparrow Academy will inherently bring in new plotlines for Umbrella Academy season 3 that may be very different from what has been shown in the last two seasons. From a tense rivalry between the two teams to a begrudging amnesty, the new reality means that anything is possible. With the latest installment of The Umbrella Academy arriving in 2022, there’s a long way to go before more is revealed about the threats that the protagonists will face in the near future.