The 37-year-old actor is currently in talks for the role, according to The Hollywood Reporter. Mysterio, aka Quentin Beck, is typically portrayed as a Hollywood stuntman and visual effects artist who turns to a life of crime when his acting career doesn't take off.
Using his talent for creating practical special effects, Beck turned himself into a supervillain who soon gained the attention of Spider-Man. Over the years, Mysterio has been a member of A-list bad guy groups like the Sinister Six. Of course, Marvel Studios could choose to go with different comic iterations of the character, such as Daniel Berkhart and Francis Klum.
Should Gyllenhaal get the part, it would create a trend of Peter Parker (Tom Holland) facing off against critically acclaimed actors. In the first movie, Michael Keaton played one of the best villains of the MCU, Adrien Toomes/the Vulture. Speaking of Keaton, Variety has reported with certainty that he will be reprising the role of Toomes. Last we saw, he was in jail after being defeated by Spider-Man and pretended that he didn't know the hero's true identity when approached by Mac Gargan (Michael Mando). It's not outside the realm of possibility for Toomes to make a jailbreak or be released on good behavior. There might also be big plans in store for Gargan, who was both the Scorpion and a version of Venom in the comics. The formation of the Sinister Six could be in the works.
Gyllenhaal can do the whole villain shtick, soely based on his haunting performance in Nightcrawler. Still, let's not get our hopes up, because it was rumored that he might take over as Batman and he flat-out said no.
He also passed on the role of Rick Flag in Suicide Squad, so he might be hesitant to re-enter genre after starring in box-office duds such as Prince of Persia and Life. On the other hand, he has Source Code and Okja on his resume, meaning his stint in sci-fi has included some highlights.
The Homecoming sequel is set for release on July 5, 2019, with Jon Watts returning as director. Since the wheels are obviously turning, you can expect Spider-Man to Show Spoiler return from the dead after being snapped out of existence by Thanos in Avengers: Infinity War.