He is often seen in a long green cloak and recently he wears the clothes of a revolutionary. He has, what resembles, tribal tattoos on the left side of his face and spiky black hair with a widow's peak hairstyle. He is almost always seen with a sinister smile on his face.
His personality is mostly unknown due to the many mysteries surrounding him, save for an apparent love for freedom and belief in fate, which are traits of a D. Unlike other members of his family, or D's for that matter, he looks stern and serious. However, in all his appearances so far, he wears a smug grin. He speaks as though he is a mystic of sorts. He didn't like to speak or be asked about his past. He also has a strange habit to always look toward East Blue when he is "feeling" the wind. His revolutionary comrade Emporio Ivankov attributes this to his instincts, having left Luffy in East Blue. Iva also says that Luffy's will to live and his phenomenal strength only help solidify the idea that he is Dragon's son. This implies that Dragon has similar willpower and strength.
Emporio Ivankov, being the former queen of Kamabakka Kingdom, is one of Dragon's comrades and one of the commanders of his revolutionary army. Ivankov apparently understands Dragon's habit of looking at the direction of East Blue whenever the winds blow, as though he is homesick.
Due to the fact that he is the leader and main center of the largest anti-government organization in the world, he has been dubbed the most dangerous and wanted man by the World Government. As stated by Robin, many people and organizations (especially pirates) would try to steer clear of disrupting the World Government and drawing attention to themselves. However, the organization which is led by Monkey D. Dragon does the exact opposite. Although many people call him a revolutionary, the World Government feels that his ideals and goals can collapse the strength and justice of the World Government. So far, it seems the World Government is the only known enemy of Dragon.
Monkey D. Garp
Dragon is the son of the well known vice-admiral Monkey D. Garp. No direct interaction has been seen between the two. However, Garp was casual towards telling Luffy about Dragon's role while he picked his nose. He even laughed when he realized he shouldn't be telling people that kind of information. There appears to be some sort of interaction between the two, as Garp stated, that the reason why Dragon was in Loguetown, was to see Luffy set off to the Grand Line.
Monkey D. Luffy
Luffy is Dragon's son. Like his father Garp, he seems to hold high expectations for Luffy. Although he has not introduced himself to him, he seems to support his son's actions so far. He also appeared in Loguetown to see Luffy off to the Grand Line and stopped Smoker from capturing Luffy. This shows that he has some care for Luffy's well being.
No mother or wife has been named for Dragon. However, both were left as "?" in the supplement issue The Grand Line Times. As a carrier of the Will of D, he may also be related to other D's. It is unknown if Dragon is aware of Ace's adoption into the family, or if Ace is the son of Gol D. Roger. This technically would make Dragon the adoptive father of Ace. However, Ace is aware that Dragon is Luffy's father.
Abilities and Powers
Little has been revealed about Monkey D. Dragon's abilities. However, he is the leader of the Revolutionaries and has full command of the organization. There have been some hints that Dragon may be an incredibly powerful person, since the World Government has dubbed him as the "World's Most Wanted Man" and that they greatly fear the possibility of warring against him along with Whitebeard, who is already a powerful threat in his own right, as well as having powerful subordinates such as Emporio Ivankov and Inazuma who are in comparison, lower in rank. This only speaks volumes of Dragon's true power.