4) Black Siren
The Lance girls got the short end of the stick while on Arrow as both came to their untimely deaths (even though one was in fact resurrected later on), but no character on the series was treated as poorly as Laurel Lance.
Katie Cassidy’s heroine was always being either harshly critiqued by fans who feared her getting in the way of Oliver and Felicity’s romance or the showrunners who didn’t know how to properly utilize one of the most iconic characters from the DC superhero universe.
[zergpaid]Black Siren, her Earth 2 doppleganger introduced in season two of The Flash, isn’t a perfect fix, but at the least we could see Cassidy on our screens again and with the canary cry in her arsenal. Like Captain Cold and Heat Wave before her, she could be the rogue villain turned heroic by the end of the season. Plus, think about the dynamics she might share with Sara.
Even better, though, would be to pull some timey-wimey nonsense, retcon Arrow‘s terrible decision to kill Black Canary off for nothing more than shock value, and bring her onto the team.