10 Characters That Could Appear In The Arrowverse
7. John Stewart
Show: Arrow
John Stewart is a former military man and a character that would later go on to become a Green Lantern. We have already seen a brief Hal Jordan cameo in Arrow Season 4, so it is possible we'll see Stewart at some point in the Arrowverse. Considering how Stewart was in the military, much like Diggle, it's possible that the two could have some connection.
As Arrow is full of characters at the moment, it is admittedly hard seeing Stewart having anything more than a reoccurring role. It's also highly unlikely that Stewart would appear AS a Green Lantern, but the character is still useful. He is headstrong, has an unbreakable will, a skilled architect, and is a master at hand-to-hand combat. These are traits that would fit perfectly in Team Arrow as he could be a good adviser for Oliver and a good friend for Diggle.
Many fans just want to see more of the characters they love exist in this universe, and the Green Lantern Corps. has been teased in the Arrowverse. It is highly likely at some point or another we get another Green Lantern reference in the show, but let's hope it's not a Guy Gardner reference.