Arrow is getting a mysterious new villain for its 6th season. At San Diego Comic Con it was announced that Michael Emerson would be joining the cast of the popular CW superhero show in an undisclosed role. He joins Kirk Acevedo who is playing the season’s other big bad Ricardo Diaz/Richard Dragon.

Season 5 of Arrow brought Oliver’s (Stephen Amell) story full circle. It closed out the flashbacks of his time on the island which have been an integral part of the show since its inception. Rather than focusing on the mystical and magical of seasons past the show came back to its more grounded roots. One of the strongest parts in all of this was Josh Segarra’s chilling portrayal of Adrian Chase/Prometheus. He proved to be a strong foe up until the finale’s crazy cliffhanger that saw Chase’s death at his own hand and the island Lian Yu blown up in an explosion leaving the characters’ lives hanging in the balance.

And it looks like the villains are only going to get better. In an interview with TV Line co-showrunner and producer Wendy Mericle has already praised Emerson’s performance.

Mericle has also teased a little of what to expect from Emerson’s character. The actor is best known for his roles playing pretty evil - or at least morally gray - characters, from a serial killer on The Practice to the puppet master Benjamin Linus on Lost. It looks like he is bringing some of his skills now to his role on Arrow.

He is a dream to work with, and I think he’s doing an amazing job. We’ve seen some dailies of some of his episodes and he’s just fantastic. He’s a really understated, subtle actor, and that brings a different energy on set. It’s great.

This character that we’re having [Michael] play is somewhat similar to people has has played in the past. But we had many conversations with him about how to make it different, and what elements we could bring to the character to change it up.

Arrow has had a number of strong villains over the years from Prometheus to Damien Darhk (Neal McDonough) and Slade Wilson/Deathstroke (Manu Bennett). A hero is only as strong as his villains and having an actor of Emerson’s caliber join the cast will only make the show better as it gives Oliver and company someone else to test themselves against.

Besides the new characters Deathstroke is also slated to return to Arrow this season. However, it is uncertain whether he will be an ally or an enemy. It also seems that Felicity’s (Emily Bett Rickards) involvement with Helix and their leader Cayden James isn’t over either. Looks like the members of Team Arrow who survive the explosion are going to have a lot on their hands this season.

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The season 6 premiere of Arrow, titled ‘Fallout’, will air Thursday October 12 at 9 PM on The CW.