SPOILER WARNING: The following story contains spoilers for last night's episode of "Arrow."

Since the first promos for Season 4 were released, "Arrow" fans have been steeling themselves for the loss of a major character. Throughout the season, a scene showing Oliver Queen -- and sometimes Barry Allen -- at the gravesite of a mystery character has haunted viewers, and given birth to numerous theories as to who Team Arrow will be bidding farewell to.

"Arrow" Recap: Felicity Gets a Code Name, Andy and Diggle Protect A.R.G.U.S.

Last night's episode, "A.W.O.L.," may not have answered the question of whose grave Ollie will eventually visit, but it featured the death of a major character nonetheless.

In a legitimately shocking scene, Shadowspire's Lieutenant Joyner (Erik Palladino) turned a hostage situation into an execution, shooting and killing A.R.G.U.S. chief Amanda Waller at point blank range.

Upon breaking into A.R.G.U.S., Joyner and his men took everyone in the facility prisoner, including Waller and Lyla Michaels. When Lyla explained that hostages or no, her boss would never give up the code for something called "Rubicon," Joyner cut his losses, and removed Waller from the equation -- permanently.

While she wasn't a series regular, Waller, played by Cynthia Addai-Robinson, was a major part of "Arrow's" second and third seasons. As the head of A.R.G.U.S., she put together the Suicide Squad, and was alternately instrumental in helping Oliver, Diggle and the rest of Team Arrow in their work, or in impeding their progress, depending on where her and her organization's interests were focused at the moment.