Lyndon Baines Johnson (August 27, 1908 – January 22, 1973), often referred to as LBJ, was the thirty-sixth President of the United States from 1963 to 1969. Johnson served a long career in both houses of the U.S. Congress, and in 1960 he was selected by then-Presidential candidate John F. Kennedy to be his running-mate. After Kennedy won the 1960 presidential election, Johnson became the thirty-seventh Vice President, and in 1963, he succeeded to the role of presidency following Kennedy's assassination. He was a major leader of the Democratic Party and as President was responsible for designing the Great Society, comprising liberal legislation including civil rights laws, Medicare (health care for the elderly), Medicaid (health care for the poor), aid to education, and a "War on Poverty." Simultaneously, he escalated the American involvement in the Vietnam War, from 16,000 American soldiers in 1963 to 550,000 in early 1968.

He was elected President in his own right in a landslide victory in 1964, but his popularity steadily declined after 1966 and his reelection bid in 1968 collapsed as a result of turmoil in his party. He withdrew from the race to concentrate on peacemaking. Johnson was renowned for his domineering (or dominating) personality and the "Johnson treatment," his arm-twisting of powerful politicians.

Johnson died after a heart attack, the third in his lifetime, on January 22, 1973.