Enderdragons are large black dragons with glowing purple eyes and grey spikes and horns. They have six limbs; two wings and four legs. They fly, and some are able to spit energy charges and acid from their mouths. They generate many ender-crystals on birth, which allow them to regenerate quickly.
They have no known diet. They might not need food due to their crystals, or they could eat endermen that live in the end dememsion. They most likely eat any humans that come in their realms.
Not known, however, they most likely originate from the end, since almost all of them are found there.