Jason Schwartzman voices The Spot, the film's primary villain. Originally a scientist by the name of Dr. Jonathan Ohnn, The Spot used to work for Dr. Ock in her lab. At one point, he explains that Miles hit him with a bagel while he and Peter B. Parker were trying to escape the lab in the first Spider-Verse film.
Unfortunately for The Spot, he was also present when Miles blew up the Super-Collider at the end of the first film, which gave him the power to open multi-dimensional portals. This overwhelming ability eventually got him fired from Alchemax. As a result, he decided to become Spider-Man's nemesis and enact revenge.
During the film, he's introduced as a somewhat clumsy villain that poses little threat to Miles or his friends. Before long, though, he learns to harness his powers for evil and manages to supercharge himself. As a major threat to the multiverse, The Spot quickly becomes one of Miles's greatest enemies. Though we don't see him make any attempt to enact his full revenge in the movie, Miguel makes it clear that The Spot is destined to kill Miles's father, a fate the young Spider-Man scrambles to prevent.