Rainbow King

The Rainbow King is a male character who is the ruler of the Rainbow Kingdom. He has a cousin who is over 1 million years old named Glummy Glooma. It's unclear if Rainbow King is connected to Glummy's uncle Grump.

It's unclear whether he has any relation to the other monarchs, Day Queen and the Night Queen, sisters who are in control of the sun and moon.

Personality
The Rainbow King is elegant and cares for every citizen of the Rainbow Kingdom. He is kind, sympathetic, and humble. When in exclamation, he uses unique phrases such as "flabbergasting fuschia". Though he possesses a wealth of knowledge, he shares his wisdom in riddles adding fun complexity to True’s adventures. He will do anything to help True on her journey but he knows that “true” success is achieved when True solves problems all on her own.

Appearance
The Rainbow King is small in size and white in color. He has signature red, yellow, and blue spheres on his head, on the left, top, and right sides, respectively. He wears a red cape and carries a golden scepter.

Grizelda
Even though Grizelda is unofficial royalty, the Rainbow King doesn't seem to mind Grizelda coming along with him when partaking in duties such as participating in the Neverending chit-chat council.

The Living Sea
He and the Living Sea have a close friendship, and according to the Rainbow King, they've known each other since the Living Sea was just a little puddle.

Rainbow Castle guards
The Rainbow King and his castle's guard are often seen together during his appearances. They have been seen chauffeuring him, building a sand castle for him, and more.

True
The Rainbow King and True appear to have a special friendship with each other, to where he even trusts her with "castle-sitting" in "Frookie Sitting". In "A Royal Stink", the Rainbow King recognized True as the honorary queen for the day.

Trivia

 * He is known to use phrases relating to color for exclamation. These phrases include:
 * "Tickle me pink!" (in "Super Duper Dance Party")
 * "Gray clouds!" (in "Super Duper Dance Party")
 * "Polka-dot pink!" (in "Frookie Sitting")
 * "Flabbergasting fuchsia!" (in "Frookie Sitting")
 * "Brilliant blue!" (in "Zappy Cling")
 * "Fluorescent fuchsia!" (in "Zappy Cling")
 * "Silver sparks!" (in "Zip Zap Zooooom!")
 * "Sapphire periwinkle!" (in "A Royal Stink")
 * "What in the big blue world is happening?" (in "Little Helpers")
 * ”Now, now, no need for a turquoise tizzy...” (in “Little Helpers”)
 * "Leapin' lime green!" (in "Wishing Heart Hollow")
 * "Sweet yellow sunny sunshine!" (in "Wishing Heart Hollow")
 * "Sapphire blue!" (in "A Berry Big Mystery")
 * "Petrifying purple!" (in "A Berry Big Mystery")
 * "A giggly green morning to you, True and Bartleby." (in "Hino Tari Hullabaloo")
 * "Golden gardenias!" (in "Hino Tari Hullabaloo")
 * "Purple persimmons!" (in "Hino Tari Hullabaloo")
 * "Oh, leaping lemon yellow. Now I'm a bee!" (in "True Switcheroo")
 * "Shocking pink!" (in "The Living Sea")
 * He shares a very similar color scheme with Bingo-Bango. It is unknown if they have any relation.
 * When not in flight, he uses the help of the Rainbow Castle Guards to travel.
 * He treats Zee as an apprentice.
 * In "Zip Zap Zooooom!" he reveals that he once used to race using his "Rainbow Racer" with one of his guards. He later became an officiator for the annual Great Rainbow Rally in the same episode.
 * In "True Switcheroo", he briefly switches bodies with a bee as a result of the Switcheroo, but he seems to enjoy it while it lasts. He and the bee are later switched to their correct bodies.