Negaonic the Hedgehog is an evil red mutated hedgehog. A older evil clone version of Sonic the Hedgehog, he was created by his arch enemy Dr. Robotnik while he was trying to clone Sonic the Hedgehog.
History
Angry and frustrated about his failures at destroying Mobius and obtaining Sonic the Hedgehog as his own adopted nephew, Dr. Robotnik begins to lose control of himself. He decides to create a clone of the hedgehog by secretly taking DNA samples from him from their battles. Being a scientist, he begins to engineer clones in a secret facility in Death Egg.
Much to his dismay, the clones of Sonic are very unstable, and melt back into ectoplasm every time he tries to make one. However, the one clone that survives was one where he apparently switched a chromosome and created a slightly older, evil version of Sonic. Although he is stable and uses her powers, he doesn't begin to melt into ectoplasm like the previous clones did. Dr. Robotnik realizes that she will do anything for her "father" who he believes hates him very much, so he decides to use him as one of his pawns to get to Sonic. He calls her "Negaonic." He sends her on a mission to get Sonic the Hedgehog, and tells her that if she does, he can use his "mid-morph" DNA to help stabilize hers. He really plans to get Sonic's "mid-morph" DNA to create a better clone, and not help her at all.