Age: Several hundred dozen years of age (approx 3,021 years of age, apparently still a young Night Fury)
Gender: male
Race: Night Fury dragon
Appearance: (As human) a scrawny Asian like young man who looks and appears very cheerful, yet slightly.... crazy, bright catlike blue eyes. Ink black hair. In this form he is dressed almost always in a jet black suit, with white tie and dark purple shirt. (As dragon), Sleek large wings (approx wingspan of 15 meters per wing), with two smaller wings for counter balance. His tail (now healed after Hiccup had passed away) acts similar to a helicopters rudder, keepnig balance and speed consistint. His eyes are green and catlike, his mannerisms are that of a feline in this form
Theme song(s): http://youtu.be/oIfiVTrgeHI
Picture(s):
Dragon form:

Human form

Toothless is a silly man, sometimes borderline nuts, and other times just plain overall silly. He works hard to keep those that he sees as friends safe from harm and is always ready for a good game of football (American) Of bowling (in which case he has a rider on his back and he driops rocks on old tanks or into caves or whatever)
Extra note: It is said that when he speaks, he sounds like Emeinem. And his mindvoice is childlike, and seemingly careless. Yet he is very protective of those he consideres his friends.
Just a simple pack witrhin which he keeps Hiccup's ankle after their fight against the Red Death, This pack is visible when in human form in the shape of a belt of sorts. when he is in dragon form the pack is seen more or less as a harness wherein Hiccup would have sat between his wings.
Toothless has one child, her name is Ixu Shen, she was adopted into a family od dragons disguised as humans at his insiting. Toothless visited the family every now and again in the guise of a older monk. Fann, a good dragon friend of his desperately wanted a child of her own. However she was a servant to a much larger family, so Toothless gave Ixu Shen to Fann, on the condition that her true heritige must never be told, She must find it for herself. Fann agreed.
It was a sad day when news of Fanns passing reached his ears, Toothless went to sleep off a driunking hangover for several days, just sitting and thinking and walking in the woods. It took two weeks for him to come to grips with his friend's death. But he knew for a fact it would take longer for his daughter to come to grips with it.