The Unholy Offspring of Lightning and Death itself.

He has jet-black scales covering his whole body, his sides having small light patches in a pattern similar to that of a manta ray. Toothless possesses two sets of wings (one main pair and one smaller pair near the base of his tail). He is missing the left side of his tail-fin, which he lost when Hiccup took Toothless down with his Mangler. This is later replaced by a mechanical fin that Hiccup constructs himself. Toothless has a rather large scar on his right shoulder/neck which is around a foot in length with a width of about an inch. Toothless's eyes are a bright green. They are located very near the front of his face giving him excellent depth perception and reflexes in flight. He can narrow his pupils to slits when threatened or angry, similar to that of a cat. But when he is docile or happy, his pupils dilate and become more dog-like. Toothless gets his name from his sets of retractable teeth. Toothless is the only Night Fury seen thus far in the franchise, so his physical appearance is all that can be studied to learn about Night Fury anatomy. He has two extremely large wings that allow him to do a vertical takeoff. Behind that is a set of smaller wings that aid in gliding. At the end of his tail he used to have yet another two wings that aided in steering and stability, but his left one is now missing.

Toothless Wiki[howtotrainyourdragon.wikia.com]
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