The Backrubbers are a species that appears in "The Other Tarts" for the annual Back-Rubbing Ceremony. They presumably have some influence over the Candy Kingdom, since Princess Bubblegum regards the ceremony as important. In "Paper Pete," one can be seen reading in the Library.
The Backrubbers are oval-shaped creatures. They are generally blue or green. They all have varying symbols sticking out of their heads, similar to antennae of some sort. They have short legs with relatively long arms, making their hands almost touch the floor. One of them is notable for being the only purple member of congress, possibly denoting him as the leader.