The Knights of The Sun were a group of loyal servants to the monarch of the Sun. They first appeared in the 9th episode of season 6.
They were first seen procuring sandwiches from an infamous intergalactic restaurant that sat on an astroid. There, they would be acquainted with Morty, whom they would implore to join their cause. After successfully convincing Morty to join them, he then quickly began to regret his choices as the entrance ceremony to become a knight requires him to sever his manhood.