After my last thread, which was mocking in nature, this one's serious. Who do you think should be the main villain in Arrow's fourth season, if ever it should get one?

SPOILERS for anyone not caught up with the show. Read at your own risk.

Me personally, I'd rather they not use Merlyn again, since he's already been the Big Bad for Seasons 1 and 3 (sharing the latter with Ras) and featured in Season 2 as well, so I think we could stand to have someone else. Deathstroke's role in Season 2 had a lot to it, and I think after all of the emotion in that season (including the death of Ollie's mother), it would be rather anti-climactic to use him again.

So who would I like to see? I'm thinking one of three candidates:

Like Father, like Daughter

Nyssa

A sort of successor/revenge story. Nyssa's not really known for her ability to be reasonable, and when (or if) she learns that Thea killed Sarah, that the former was not in control will be of no consequence to her. She'll probably seek vengeance, and especially if by that point Ras al Ghul has met his end, and even more especially if Merlyn (who Arrow is/was protecting) has a role to play in it. Between it all, the likelihood of Nyssa getting more reason to hate Arrow is high, and there is always the possibility she could succeed her father as the League's leader. This would allow her to become a major player, and also keep the League in the show after the third season. Another possibility (if not also a longshot) is Nyssa trying to corrupt Laurel and get her to replace Sarah in the League, also perhaps becoming attracted to her as she was to Sarah. Basically, Laurel would be caught between the two sides of the conflict, which would also facilitate her transition from brutal anti-hero to more traditional hero (assuming that doesn't happen in Season 3 of course).

This city's mine now little man.

Brick

Brick's been confirmed to appear in Season 3, but so long as he doesn't get offed during the course of that season (or else indisposed in some way), I could see him stepping up to become the main foe of Season 4. If so, I could see Brick becoming an almost Kingpin like antagonist, as in an untouchable and physically imposing crime boss who gets Starling City firmly in his pocket, and then Arrow has to fight to get his city back. This would also hopefully mean that the Season 4 finale is not another terrorist attack on Starling City, which we've already gotten two of and likely soon to be three. So if the main villain is more of an "at home" threat who wouldn't want the city destroyed (because then he can't make a profit), it would hopefully keep the finale from feeling like a re-hash of the earlier ones. Best of all, Brick is strictly a Green Arrow villain, which would make his being the main villain make Arrow feel more like...well, a Green Arrow show.

You should know better than to stand in my way Oliver.

Amanda Waller

I actually think this one is the one most likely to happen. We've already seen plenty of examples of Waller's very loose moral compass and definitions of right and wrong, and her clashes with Oliver in the past, so having a situation where Arrow's very presence gets in the way of her plans would not necessarily be out of the question. Having Waller as a Big Bad could also really shake things up for several reasons:

• Waller knows who Oliver is, and could blow the whistle on him and thus expose his secret identity for good. This could be a good way to change up the status quo of the show, and really make things more of an uphill battle for Ollie.
• Diggle's wife being loyal to ARGUS (to a point) will likely prompt some...problems, between her and Diggle, and also put their child at risk (and I wouldn't put it past Waller to threaten Lyla's daughter to force her cooperation).
• It would make a return appearance by the Suicide Squad very likely, with Deathstroke and Captain Boomerang possibly returning as Squad members. In fact, Waller's letting Slade loose might be one of the main catalysts behind her and Ollie's coming to blows.

So what do you guys think? Which villain (or villainess) do you think is most likely to be Season 4's big bad? Do you think I missed any other viable candidates? If so, share your thoughts below. I still think these three are the most likely candidates, but who do you think will be Season 4's main villain?