Willem DaFoe, who played Norman Osborn a.k.a. The Green Goblin in Sam Raimi's Spider-Man, and who had brief cameos in both of the sequels, apparently isn't closed to the possibility of appearing in the fourth Spider-Man movie, if it would be fun to do. DaFoe revealed the news to iF Magazine while being interviewed about his latest film, Anamorph.
When asked if he would be willing to reprise his role, DaFoe responded:
While not exactly a solid "yes", it does seem like DaFoe would be open to the possibility. The real question is whether or not fans and the filmmaker want to continue the Goblin saga on into a fourth Spider-Man film.