The Night Queen is one of the two official queens of the Rainbow Kingdom, responsible for bringing moonlight to the Kingdom on a daily basis. She is the sister of the Day Queen, whose purpose is to raise the sun when it becomes daytime.
The Night Queen, like the Day Queen, originally believed that the nighttime is the best time (and later went on to sing a song about it), and would try to change her sister's outlook on it. Her sister had parallel viewpoints, but they still got along as they share sisterly love despite their sibling rivalry. They are only able to see each other at dusk and dawn when it is time to raise or lower the sun, and as a result, in "Queens of the Day and Night", they stuck the sun and the moon together so they could spend more time with each other. After realizing that the Kingdom can't function properly their way, with help from True and her Wishes, they split the sun and moon again, and were given Face Bubble sashes so they could speak to each other any time they want, even if they weren't physically with each other.
The Night Queen is white in color, like the Rainbow King. She has two blush marks on her face. She wears a purple moon-shaped headdress and an aqua and blue dress with a blue cape. She is always floating or flying, and carries a white scepter.
It is currently unknown what her exact relation to the Rainbow King is.