Credit: The CW

Warning: This story contains major spoilers on Thursday's episode of Arrow. Read at your own risk!

Arrow finally unveiled the mysterious head of Helix during Thursday's episode — though most fans had guessed his identity a while back.

After Alena (Kacey Rohl) enlisted Felicity's (Emily Bett Rickards) help in taking down Cayden James before he could enact a plan that would basically kill 300 million people, the duo were attacked by the man himself, who was revealed to be played by Lost and Person of Interest alum Michael Emerson.

When it was announced at Comic-Con that Emerson would recur as an unnamed mystery character, Arrow viewers, this one included, suspected he'd be portraying Cayden James. The character was oft-mentioned and even introduced last season, but we only saw him with a hood over his head when Felicity helped to set him free from A.R.G.U.S. custody.

Credit: The CW

Suffice it to say, freeing him was the wrong move. Cayden was the one to save Black Siren (Katie Cassidy) on Lian Yu, using her to enact his plans of essentially shutting down the internet — the collateral damage would lead to millions of deaths. Ultimately, Felicity is able to stop him, but accidentally plays right into his hands, allowing him to upload something for future needs. What those may be are shrouded in mystery. (Read Emily Bett Rickards' take on Cayden's return here.)

Arrow airs Thursdays at 9 p.m. ET on The CW.