Space Pirate Sympathisers are groups of individuals who apparently side with the Space Pirates in their "war" with the Galactic Federation. Only mentioned in the manga, it is stated that they had begun terrorist actions throughout Federation space. The Federation Police were said to have not yet regained public order on most of the planets where these beings reside, though it also mentioned that both Bounty Hunters and vigilante forces would be aiding the Federation in maintaining public order, though this information was not yet confirmed.
While numerous species make up this "organization", some likely members include the Kihunters. It is unknown whether or not entire planets, governments, or only small isolated groups sided with the pirates, or even what the pirates thought of this, though it is known that they did create enough of a threat that military force was required in an attempt to subdue them. These events only took place in the manga, and in the games it is said that they made a base on Zebes, and then moved on and on until Samus Aran ended the organization in Super Metroid.