Echidna

Echidnas in the video game, comic book, and television series fiction of Sonic the Hedgehog, are anthropomorphic, dreadlocked animals that stand out from the other humanoid animals.

Games
As seen in Sonic Adventure, the Echidnas were several thousand years ago a peaceful, Maya-like civilization that lived in the area that is now known as the Mystic Ruins. However, after a chief named Pachacamac took over after his mother, the Echidnas became a waring race, attacking and conquering the surrounding areas. After they discovered the mysterious Chaos Emeralds and Master Emerald, Pachacamac decided that the powerful gems would help them a lot in their conquest. Despite his daughter Tikal's protests, Pachacamac and his warriors stormed the altar containing the Emeralds. After harming most of the Chao living there in the process, the guardian of the Emeralds and the Chao, Chaos appeared and annihilated most of the Echidnas in a fit of rage. Tikal managed to seal the angered creature and herself inside the Master Emerald, and the island that the Master Emerald was placed upon was surged with Chaos energy due to the lack of Chaos Emeralds to neutralize it, and the island was sent into the sky along with the surviving Echidnas.

The surviving Echidnas named their new airborne home Angel Island, and promised that the Master Emerald would never be harmed. They apparently tried rebuilding their civilization on the island, as it is filled with ruins from a city, a complicated water system, and a pyramid. They also built the Hidden Palace, a new altar for the Master Emerald situated deep inside a volcano, and the Sky Sanctuary, a group of ruins hovering high above the island itself. Several thousand years later, Knuckles the Echidna was the only Echidna left, protecting the Master Emerald with his life. Tikal's spirit can also take the form of her original body, so she may be considered a "living" Echidna.

Sonic the Hedgehog (comics)
The Sonic the Hedgehog comics published by Archie Comics, contrary to most of the storylines, features the Echidna race as alive and well. They are depicted as Mobius' most technologically sophisticated race. The Echidnas are traditionally found in one of two locations: Angel Island or the hidden island of Albion. According to Echidna culture, when a female Echidna reaches the age of sixteen, she is introduced to society as a young lady, similar to the tradition of the debutante ball. A Echidna sixth sense called the the Soultouch allows them to determine their soulmate simply by laying eyes upon them.

Albion
The original homeland of the Echidnas, Albion is an island located near Mercia. For many years, the people lived there in contentment. However, there were those among them who were adventurous, and they departed, later going on to found Echidnaopolis. Albion is home to Councilor Gala-Na, a female Echidna who seems to be very self righteous. In the past, she has used Albion's facilities in attempts to disassemble Mercia's Roboticized High Sheriff and to forcibly extract the Chaos powers of Knuckles the Echidna. As a result, Albion has become alienated from the rest of Mobius. In the ancient past, the Albion Knights of Aurora were responsible for the defeat of the original Order of Ixis.

Echidnaopolis
The only city on Angel Island, Echidnaopolis was founded centuries ago by travelers from Albion in the country of Down Unda. They remained there for many years, until the city was threatened by the White Comet. Knuckles' scientist ancestors used the energies of 7 Chaos Emeralds to lift the city and part of the surrounding landscape into the sky, leading to the creation of Angel Island, which was named for the female Echidna Angel-La. Part of the population left before the city was raised, becoming the Lost Tribe, which eventually found its way back to Albion.

For the past few centuries, Echidnaopolis has become embroiled in war as its citizens battled the Dark Legion, a group of technocrats who broke off from the main population of Echidnas in the city. To protect it from nuclear attack, the city was beamed into another Zone for a time, and only returned when the barriers were erased by Dr. Robotnik's Ultimate Annihilator. It now serves as the home for the more important Echidna characters, and also for the Chaotix, Knuckles' allies.

Portal
Angel Island's second city first appears in Mobius: 25 Years Later. The gateway city of Portal functions as Angel Island's chief link of commerce and travel with the mainland continents of Mobius. King Sonic is found here by Tails and Lara-Su following the alteration of the timestream.

In Sonic the Comic
8000 years in the past, the ancient Echidnas had established a technologically advanced civilisation (hunting the Kohenyu dinosaur species to extinction in the process) based in Megapolis City. This would be lost when the alien Drakon Empire invaded, looting the Echidna's sacred emerald mines and using the emeralds within as a source for their unstable Chaos Energy, intending to manufacture thousands of Chaos Emeralds and conquer the universe with them. Only seven were created, at which point the Echidnas under Pochacamac stole them; the Great War between Echidna and Drakon broke out soon after.

In the present day, the Echidnas have all disappeared and nobody knows what happened to them. The Floating Island is covered with crumbling ruins - Megapolis, a few Zones such as Sandopolis, the ancient portals to the Special Zone (known to the echidnas as the Nightmare Country) and the Emerald Chamber, where the Chaos Emeralds reside. The main relics of this time are the Emeralds, the ancient Guardian Robots, and the ancient computer systems that control the path of the Floating Island, maintain its forcefield, and in times of real danger can fire energy blasts at enemy aircraft.

Knuckles is one of the only two living Echidnas; originally he lived as a warrior in the ancient past, fighting against the Drakons, but through means unknown he lives in the present as the Guardian of the Chaos Emeralds and has no memory of his past or his lost people. The other surviving Echidna is Doctor Zachary, an evil and aged cyborg misanthrope who wants to destroy the Floating Island and Mobius, and his origins are unclear.

The unofficial online continuation Sonic The Comic - Online! expanded Echidna lore. The ancient Echidna princess and mystic Tikal was brought to the present, though she lost her memories, and it was revealed that the Emerald Hill Zone gained its name from the fact shards of the Chaos Emeralds were hidden in a bunker there by the Echidnas during the War. It also introduced Vichama, a seemingly powerful and murderous Echidna; in actual fact, the Echidna was just a vessel possessed by a spirit calling itself the God of Death, who killed hundreds in the ancient past before it was imprisoned. Vichama recently left his vessel and Tikal has had a vision that he will return to the Floating Island.

In Sonic Underground
In the cartoon series Sonic Underground, two specimens of the Echidna race are known to exist: Knuckles and his great-grandfather Athair. It is unknown what has happened to the rest of the species, as the show did not go in depth on the situation. However, judging by the almost legendary status of Knuckles among Mobians, it is likely that the rest of the species is either extinct or lives in a hidden location. That said, in one episode Knuckles is shown giving orders to unknown persons manning anti-aircraft guns, and it was never explained who was doing that (though it's possible it was a form of computer system).

In Sonic X
The anime series Sonic X follows the plot of the more modern Sonic the Hedgehog games, with Knuckles and Tikal as the only Echidnas remaining, the rest having been destroyed by Chaos. The only major difference is that the ancient Echidna civilization came from Sonic's homeworld and that the ruins were transported via Chaos Control, instead of them being on Earth all along like in the games.