While the titan Kronos' involvement in the plot was revealed in Episode 7 of DIsney+ adaptation, he finally appeared on-screen (as well as he can while still disembodied) in the show's finale.
So, who exactly is Kronos?
Percy Jackson Show Confirms Kronos
Warning: This article contains spoilers for Percy Jackson and the Olympians on Disney+, and The Lightning Thief by Rick Riordan.
Throughout the Season 1 finale of Percy Jackson and the Olympians on Disney+, Kronos' name was uttered several times.
Then, the Titan lord made a disembodied, spirit-like appearance in Percy's dream, leaving no room for doubt that the voice speaking in Percy's nightmares was his all along.
In both the books and the show, it is revealed at the end of the first story that Kronos manipulated Ares and Luke Castellan into stealing Zeus' Master Bolt, and betraying the Olympians by serving him.
Percy figured out Kronos' involvement back in his conversation with Hades in Episode 7, but Episode 8 revealed the full extent of his plot, and saw Percy and Kronos actually talk to one another through Percy's dream. Until this point, all their conversations were one-sided.
Percy recognizes how much of a thread Kronos poses — so much so that he risks his life and safety to go to Olympus himself and tell Zeus about Ares' betrayal, and Kronos' attempt at a return from his imprisonment in Tartarus (where he was left, chopped into many, many pieces).
Who Plays Kronos In Percy Jackson's Show?
Throughout Percy Jackson and the Olympians, actor Nick Boraine has been voicing the creepy, raspy voice in Percy's nightmares, aptly credited as "Voice in Dream."
Episode 8, however, sees the NCIS and Black Sails (a show sharing much of Percy Jackson and the Olympians' creative team) alum officially credited as "Kronos."
This implies that if Percy Jackson and the Olympians does get renewed for more seasons, Boraine will appear as the villain as the story needs him.
Warning: The following section contains spoilers for The Battle of the Labyrinth and The Last Olympian by Rick Riordan.
In the books, Kronos never actually takes on his own form. Until The Battle of the Labyrinth (Book 4), Kronos basically only appears as a voice and presence in Percy's dreams.
In the show, this will theoretically be adapted as the creepy, gray, cloaked figure seen in Percy's nightmares thus far.
Then, at the end of The Battle of the Labyrinth, and for all of The Last Olympian, Kronos inhabits the body of Luke, until Luke sacrifices himself in order to bring Kronos down with him.
As such, it is unclear whether Boraine will actually ever appear as the Lord of the Titans, or if he will simply voice the character in his various forms, assuming the show continues.
All eight episodes of Percy Jackson and the Olympians Season 1 are available to stream on Disney+.