Variety reports Williams will join Tom Hardy and Riz Ahmed in the Marvel Comics flick, which centers on Spider-Man's anti-hero nemesis, although Spidey won't be in the movie. Ruben Fleischer (Zombieland) is directing, with Hardy set as Eddie Brock/Venom, Ahmed possibly as his foe Cletus Casady aka Carnage, and Williams as a district attorney and possible love interest.
It's still unclear how close to Venom's origin will be retained, especially since it ties so closely with Spider-Man. Brock was a jealous photojournalist who bonded with the alien symbiote previously rejected by Spider-Man.
Venom opens October 5th 2018. Williams will be seen next in Ridley Scott's All the Money in the World, and later opposite Hugh Jackman in The Greatest Showman.