Monkey D. Dragon

Japanese name:	モンキー・D・ドラゴン
Nickname:	The World's Most-Dangerous Criminal, "The Revolutionary" Dragon

Monkey D. Dragon is the father of Monkey D. Luffy and the son of Monkey D. Garp. He is the infamous Revolutionary leader who has been attempting to overthrow the World Government. He is the World Government's greatest enemy and is the most dangerous and most wanted man in the world.

Dragon's personality is mostly unknown due to the many mysteries surrounding him, save for an apparent love for freedom and a belief in fate, traits of a "D".

But unlike other members of his family, or D's for that matter, he has a stern and serious demeanor, however in all of his appearances thus far, except at Roger's execution, he is seen with a smug grin on his face. However, years prior to the main story he was seen rather shocked when hearing the reason of Sabo's plea for help and rejection of his own Noble heritage.

He also seems to care about innocent people, as shown where he willingly saved the people of the Gray Terminal and allowed them to join the Revolutionary Army.

He speaks as though he is a mystic of sorts and apparently doesn't like to speak of, or be asked about, his past. He also has a strange habit of always looking towards the East Blue when the wind changes. His revolutionary comrade Emporio Ivankov attributes this to his instincts, having left Luffy in East Blue.

One Piece Wikia