King Boom Boo is a malevolent ghost who has previously tangled with Knuckles the Echidna.
King Boom Boo confronted Knuckles while the Guardian was searching for a key to help his friends Sonic the Hedgehog, Amy Rose, and Miles "Tails" Prower. He attacked Knuckles for unknown reasons, but proved to be no match for the Echidna. (VG: SA2/SA2:B)
- King Boom Boo has not appeared in the Sonic the Hedgehog comics yet; his existence was confirmed by Sonic's Monster Mash-Up!.