4) Ned Leeds
A similar character who’s sometimes on Spidey’s side and sometimes isn’t is Ned Leeds. A reporter at The Daily Bugle, Ned was caught up in a love triangle with Peter over Bugle secretary Betty Brant in the character’s early days. Much later on, he was revealed to be the supervillain The Hobgoblin.
Going from being an ally of Peter’s, to a rival, to a full-on supervillain, Leeds would certainly offer a lot of dramatic potential for Glover to play with. Introducing The Hobgoblin might also be a good move as, after every previous Spider-Man film has featured him in some capacity, The Green Goblin is pretty old hat by now. The Hobgoblin also has a creepier look, which might prove easier to adapt to the screen than the goofy Green Goblin get-up.