The Knight is a mysterious character referenced in Deltarune. While not making a physical appearance, the Knight is of seemingly higher rank than King and Queen, making them a primary antagonist. According to King, the Knight boasts tremendous power, and has the ability to open Dark Fountains and create Dark Worlds.
Before the Knight appeared, the Dark World was ruled by four kings. However, this all changed when the Knight took the king of spades (simply known as King) under their control, and the three other Kings were locked away in Card Castle. As a result, King became the absolute monarch over his Dark World. The Knight then continued to create the Eastern Fountain. The details on how the Knight has affected King, are currently unknown.
During Chapter 1, the Knight never makes an appearance. Instead, the party learns of them from stories primarily told by King and Seam. The Knight is referred to as a "strange knight." The Knight's whereabouts during Chapter 1 are unknown.
At some point during Chapter 2, The Knight created another Dark Fountain, this time forming a new Dark World from the library. During the party's battle with Queen, she explains that any Lightner with enough Determination is able to open Dark Fountains, and she was planning on replacing the Knight's abilities with those of Noelle Holiday. Ralsei then goes on to explain that the Dark Fountains, when gone unchecked, would eventually consume the Light World, turning all Darkners to stone and leaving Lightners alone in the dark. Queen claimed to be oblivious of Knight's true motives. At the end of Chapter 2, Kris, or some entity controlling them, is seen opening a new Dark Fountain in their home.
- In Toby Fox's commentary on the Game Main Theme (Piano Sketch) scrapped Deltarune track, it is implied that the Knight is the main antagonist and final boss of Deltarune.
- King refers to the Knight as "my Knight" in the same way a subject might refer to their ruler as "my King," swearing not to let the Knight down.
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