Lyndon Baines Johnson (August 27, 1908 – January 22, 1973), often referred to as LBJ, served as the 36th President of the United States from 1963 to 1969 after his service as the 37th Vice President of the United States from 1961 to 1963. He served in all four federal elected offices of the United States: Representative, Senator, Vice President, and President.

Johnson, a Democrat, succeeded to the presidency following the assassination of President John F. Kennedy, completed Kennedy's term and was elected President in his own right, winning by a large margin in the 1964 Presidential election. Johnson was greatly supported by the Democratic Party and, as President, was responsible for designing the "Great Society" legislation that included laws that upheld civil rights, Public Broadcasting, Medicare, Medicaid, environmental protection, aid to education, and his attempt to help the poor in his "War on Poverty." Simultaneously, he greatly escalated direct American involvement in the Vietnam War.

Johnson served as a United States Representative from Texas, from 1937–1949 and as United States Senator (as his grandfather foretold when Johnson was just an infant) from 1949–1961, including six years as United States Senate Majority Leader, two as Senate Minority Leader and two as Senate Majority Whip. After campaigning unsuccessfully for the Democratic nomination in 1960, Johnson was asked by John F. Kennedy to be his running mate for the 1960 presidential election. Johnson's popularity as President steadily declined after the 1966 Congressional elections, and his re-election bid in the 1968 United States presidential election collapsed as a result of turmoil within the Democratic Party related to opposition to the Vietnam War. He withdrew from the race to concentrate on peacemaking.

Johnson was renowned for his domineering personality and the "Johnson treatment," his arm twisting of powerful politicians in order to advance legislation. He was a legendary "hands-on" manager and the last President to serve out his term without ever hiring a White House Chief of Staff or "gatekeeper" (a position invented by Kennedy's predecessor, Dwight Eisenhower).

Johnson's escalation of the Vietnam War ruined much of his credibility as President. Johnson was wary of potential political attacks from the right for losing a portion of the world to communism. Johnson believed that if Vietnam fell to the Communists, his presidency would be considered soft on communism, at the same time undermining his grand domestic agenda. Johnson began bombing North Vietnam in 1965 and it continued for the next 7 years through the Nixon Administration. Over time, Johnson escalated the number of troops and active military involvement in Vietnam. Soldier casualties were mounting and soon chants were heard, "Hey, Hey LBJ, How many kids did you kill today?" By the end of his presidency, Johnson turned into a recluse, rarely leaving the White House.

Johnson died after suffering his third heart attack, on January 22, 1973. He was 64 years old.