Ryuji Yamazaki is a video game character created by SNK, and one of the characters featured in the Fatal Fury/Garou Densetsu series of fighting games.

According to his official biography, Yamazaki was born on August 8, 1964. He stands 1.92 m (6'3") and weighs 96 kg (211 lbs). His blood type is A. His hobby is collecting knives, his favorite food is basashi (horse meat), and he has no favorite sports of his own. His treasured possession is anything that financially benefits him, and dislikes labor.

Yamazaki is a self-taught brawler, and has had no parents to look up to since he was young. Respected in Hong Kong, he sported a cunning sense of crime, and was also very skilled in using his trusty knife, his eternal partner. Yamazaki also likes to dress with class, and have the highest priorities. This all changed when he and his boss went to strike a deal with another gang. With his maniacal laugh and dirty tricks, Yamazaki will do anything to win, even if an opponent is killed in the outcome. Since then, he has worked as an assassin for hire. That is because Yamazaki takes pleasure in killing people and making them suffer, and his salary is not bad, either.

One day, Yamazaki was signed up by Jin Chonrei and Jin Chonshu to protect them and the scrolls of immortality. As he was having fun at a local dojo, Yamazaki was faced by an Englishman named Billy Kane, who worked as the bodyguard of Geese Howard, main crime leader of Southtown. Yamazaki refused Billy's offer to join him and participate in the King of Fighters tournament at first, but after terribly mauling one of the warriors, he felt an adrenaline rush through his blood. Feeling a need to fight and kill, he accepted Billy's offer.

Yamazaki fought in the tournament, and both Billy and Blue Mary Ryan (his other partner) noticed how he went more and more berserk.