Arrow has the tendency to bring back some of its former cast members, this is seen with the likes of Slade Wilson and Malcolm Merlyn, both returning after they were either locked up or "dead". With Sara Lance and Ray Palmer returning for Legends of Tomorrow, one can only wonder who else will return in the show's star studded 4th season. Let me start this list off with a character who needs a well deserved second outing.
Severely underutilized to say the least, Komodo was introduced during last season's, 'Who killed Sara' arc. The show could easily incorporate him into the H.I.V.E. storyline. He could be introduced with Darhk breaking him out of prison and hiring him to take out the Green Arrow. With archery skills that could rival both Oliver and Thea, Komodo would be a great addition to season four.
This is a character that Arrow greatly messed up. Helena Bertonelli was portrayed as a psychotic ex-lover of Oliver who wound up in jail for attempting to murder her own father. I would love to see Helena break out of prison sometime soon and maybe join Team Arrow on a temporary basis. She could help Ollie with a Mafia family she plans to take down that's under Darhk's control. She would then leave to become her own hero and maybe even make a reference that she's leaving for Gotham. There have been many rumours of Helena's return, and Marc Guggenheim confirmed on his Tumblr that Huntress was poised to return in season 3, but plans never came to fruition.
Where on Earth did this guy go? He was the only character able to injure Brick with his bare hands, he taught Laurel how to fight and he even gave Oliver a run for his money, yet he just disappeared!? His last appearance was ambiguous to say the least, with some suspecting Brick killed him in their encounter, but I hope he returns to help Laurel refine her skills. You can't have Black Canary without Wildcat. His introduction also led to this epic series moment!
What an entrance this woman had on Arrow! Imean, she resurrected a dead Oliver Queen and then fought alongside Team Arrow against the League of Assassins. If that doesn't scream "please bring this character back!", I don't know what does. Laurel suggests that she come fight with them in Starling, but Katana told her she must return to a life of solitude. We all hope that she returns from her seclusion and at least makes an appearance or two.
Arguably the greatest character on Arrow, and that's including Oliver and Diggle. Slade Wilson was a character you hated to love and loved to hate, yet we were all in awe every time he appeared on screen. Whether it was beating Team Arrow single-handedly in less than a minute or killing Oliver's mother, Slade commanded and stole every scene. Some argue that the reason season 2 was Arrow's greatest season was mainly because of Slade, and I can't find a reason to disagree. With Slade being an agent of H.I.V.E. in the comics, this would be the perfect opportunity for Arrow to bring him back. Marc Guggenheim has even stated that Deathstroke's return is in Manu Bennet's (Deathstroke) hands, and Bennet has been teasing a Deathstroke return for months. After all, he still has a promise to fulfil...
With the DC Television Universe becoming a star studded affair leading up to Legends of Tomorrow, and Team Arrow looking like they will be facing their greatest threat, now would be the perfect time to re-introduce some fan favourite characters.