The Knight is a mysterious character referenced often in Deltarune. While not making a physical appearance, the current major bosses of King and Queen seem subordinate to the Knight, making it a primary antagonist.
Before the Knight appeared, the Card Kingdom was ruled by four kings. However, this all changed when the Knight took the king of spades (simply known as King) under its control, and the three other Kings were locked away in Card Castle. As a result, King became the absolute monarch over his kingdom. The Knight then continued to create the Eastern Fountain.
During Chapter 1, the Knight never makes an appearance. Instead, the party learns of it from stories primarily told by King and Seam. Seam refers to the Knight as "strange knight," and King refers to them as "my Knight" in the same way a subject might refer to their ruler as "my King," swearing not to let the Knight down. The Knight's whereabouts during Chapter 1 and the details of its encounter with King are unknown. Jevil mentions that the "Knight's hand drifts forward" after beating him via fighting.
During Noelle and Berdly's study session, the Knight created another Dark Fountain, this time forming a new Dark World from the library. A video of this event plays in a room in Queen's Mansion, but there is too much smoke to identify the Knight. Spamton, in his shop, makes the implication that the Knight has something to do with "communion," and starts to tell Kris something about them, but mysteriously cuts himself off. 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. Berdly attempts to make a fountain but is cut off by Ralsei, who 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 was seemingly oblivious to the Knight's true motives.
At the end of Chapter 2, Kris is seen ripping out their SOUL and opening a new Dark Fountain in their home. Whether this means that Kris is the Knight is unclear.
- 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.
- The Knight is alternately referred to with "it" and "they" pronouns.
- UNDERTALE 6th Anniversary So We Play DELTARUNE Chapter 1 For Some Reason - LIVE! - YouTube
- The Roaring Knight... Today, It Deigned To Create This World - Queen
- The Roaring Knight... Whatever they are, they're making these fountains... - Susie