Cromwell will play Captain Stacy, the father of Gwen Stacy, to be played by Bryce Dallas Howard, The Hollywood Reporter said Monday.
In the comic book series, Captain Stacy dies while saving a child as Spider-Man battles a supervillain. Peter Parker's girlfriend then blames Spider-Man for her dad's death.
Tobey Maguire, Kirsten Dunst and James Franco will all be reprising their previous "Spider-Man" roles. Other newcomers in the third installment include Topher Grace, Thomas Haden Church and Theresa Russell.