Daniel Ken "Dan" Inouye (Japanese: 井上 建, Inoue Ken; born September 7, 1924) is an American politician who currently serves as the senior United States Senator from Hawaii. He has been a U.S. Senator since 1963 and, following the recent death of Ted Kennedy, is currently the second-most-senior member after fellow Democrat Robert Byrd. He has continuously represented Hawaii in the U.S. Congress since it achieved statehood in 1959, serving as Hawaii's first U.S. Representative and later a U.S. Senator. Inouye was the first Japanese-American to serve in the U.S. House of Representatives and later the first in the U.S. Senate. He is the third oldest U.S. Senator after Robert Byrd and Frank Lautenberg. He is also a recipient of the Medal of Honor.

Born in Honolulu, Hawaii, Inouye is a Nisei (second-generation) Japanese-American and a son of Kame Imanaga and Hyotaro Inouye. He grew up in the Bingham Tract, a Chinese-American enclave within the predominantly Japanese-American community of Mo'ili'ili in Honolulu.

He was at the Pearl Harbor attack in 1941 as a medical volunteer.