Sansei (三世, "third generation") is a Japanese and North American English term used in parts of the world such as South America and North America to specify the children of children born to ethnic Japanese in a new country of residence. The nisei are considered the second generation; grandchildren of the Japanese-born immigrants are called Sansei; and the fourth generation is called yonsei. The children of at least one nisei parent are called Sansei and are usually the first generation of whom a high percentage are mixed race since their parents were usually themselves born and raised in America.

The character and uniqueness of the sansei is recognized in its social history.