List of Sonic the Hedgehog characters

This is a complete list of characters who have appeared in Sonic the Hedgehog in order of appearance.

A.D.A.M.
A.D.A.M., or Autonomous Digital Assault Microbe, or even A.D.A.M. determines Annonymous' Movements, is a fictional artificial intelligence and antagonist from the Sonic the Hedgehog comic series. His name stands for either "Autonomous Digital Assault Microbe" or "A.D.A.M. determines Anonymous' Movements", and he is a sentient computer virus created through accident by Dr. Eggman.

Initially, A.D.A.M. appears as simply a green computer screen, with a EKG line like that on a medical monitor which spikes whenever he speaks. When in a body composed of nanites, he appears as an amorphous green blob vaguely shaped like Eggman's icon with red eyes, a black mouth, and the word "EGG?" written across his forehead. Later, after assuming Tommy Turtle's body as a host, he takes on the form of a silvery metallic turtle with white eyes. On his chest in this form rests a green orb, surrounded by a star-like frame with several cords of metal attached. Armor in the form of a helmet also appeared around his head, matching four blade-like appendages reaching from his back.

ART
One of Doctor Robotnik's most powerful creations, ART was developed for the purpose of defeating the Sonic Underground and their Freedom Fighter allies. Able to absorb any technology into his frame to increase in size and power, ART is a learning robot, capable of adapting to anything his opponents might deploy. "ART" stands for "Artificial Robot Technology".

Aaron the Echidna
Aaron was a Mobian Echidna, the son of Rembrandt and brother of Jordan. He has the distinction of being the first Guardian of Angel Island to die childless, and before joining the Brotherhood of Guardians.

Abby
Abby is a Mobian koala who works as a housemaid 25 years into the future. In the Mobius: 25 Years Later series, Abby serves the Guardian family (Knuckles, Julie-Su and Lara-Su) and is responsible for maintaining the household. She seems to have a strong dislike for King Sonic's son Manik. She listened in on a conversation between Julie-Su, her sister Lien-Da, and Queen Sally, offering her own occasional comments. She also helped welcome the royal family upon their arrival, earning a scolding from Julie-Su for her opinion of Manik.

Abraham Tower
Abraham Tower, also known as G.U.N. Commander or simply The Commander, is the chief of the Guardian Units of Nations (G.U.N.). This gives him complete authority of all operations, and is usually seen giving missions to Shadow, Rouge, and Omega, whom he has dubbed as "Team Dark".