Jack Noir is an Agent of Derse who appears in every session of Sburb. He oversees various affairs of the kingdom and does all of the most important and most tedious paperwork, and is the direct subordinate of the King and Queen. In the kids' session, he slew the Queen, and soon after, the King, declaring himself as the Sovereign Slayer and wreaking havoc on the Medium. Karkat has identified him as the "cancer" he created in the kids' session. A "Jack" is a face card in a normal deck of cards that ranks below the king and queen, and "Noir" is a pun on the detective film genre film noir, an allusion to Problem Sleuth, and Jack's alternate universe counterpart. "Noir" also means "black" in French, making his full name a pun on the card game Blackjack. (Resemblance to the name Jack Black is just an amusing coincidence.)
