The President of the United States, also simply known as a president, is a person elected by votes as the leader of the United States of America.

The president and the vice president comprise the Executive Branch of the United States. The federal law enforcement agency attached to the Executive Branch is the United States Marshals Service, the oldest federal law enforcement agency in the United States. The home and office of the president is the White House, which is located in Washington, D.C.

George Washington was the first president. Abraham Lincoln was the 16th president and remained so up until his assassination at the hands of John Wilkes Booth on April 14, 1865.

Ulysses S. Grant, the 18th president, was in office when Marty McFly and Dr. Emmett Brown arrived in 1876 to bring Edna Strickland back to 1931.

When Doc was sent back to January 1, 1885, Chester A. Arthur, the 21st president, was still the incumbent president. By September 1885, when Marty McFly arrived, Grover Cleveland, the 22nd president, was in office. Grover Cleveland was defeated by Benjamin Harrison, but won re-election in 1892, making Cleveland the 24th president as well. Existence of other reality presidents before 1881 (John Adams, James Monroe etc.) is highly possible, but not confirmed.

Calvin Coolidge, the 30th president, was in office from 1923 to 1929. He was succeeded by Herbert Hoover, the 31st president, who was in office when Doc and Marty arrived in 1931. A campaign flyer for Herbert Hoover covered a secret switch that opened a garage door that led to "Kid" Tannen, who was holding Edna Strickland in captivity. When Doc Brown and Marty McFly departed for 1986A, Doc warned that they should leave before accidentally causing Hoover to be elected to a second term.

Franklin D. Roosevelt, the 32nd president, was in office from 1933 to 1945. He signed the executive order that authorized the development of the atomic bomb through the Manhattan Project. Doc was one of the scientists that worked on this project.

In 1955, Dwight D. Eisenhower, the 34th president, was in office. John F. Kennedy, the 35th president, was in office from 1961 until his assassination in 1963. In 1955, when Marty noted that Riverside Drive was later John F. Kennedy Drive, Sam Baines retorted "Who the hell is John F. Kennedy?" Existence of other reality presidents between 1897 and 1953 (Theodore Roosevelt, Woodrow Wilson etc.) is highly possible, but not confirmed.

Lyndon B. Johnson was elevated from his position as Vice President and became the 36th president in 1963. He won a full term in 1964, and opted not to run for a second term in the 1968 election. In 1968, he met with Nixon at the White House. Doc replaced a portrait of George Washington with a portrait of himself. A picture of Nixon and Johnson talking at the table where Doc's portrait was hung was placed in his chicken restaurant in 1993.

Richard Nixon was the 37th president. In the altered 1985-A timeline, Richard Nixon had been elected to his fifth term in 1983, with help from the rich and powerful Biff Tannen, and promised to end the war in Southeast Asia and the Vietnam War by 1985.

Gerald Ford was the 38th president, ascending to the office of the presidency when Richard Nixon resigned. In 1974, Doc Brown was present when Gerald Ford met Leonid Brezhnev in the Soviet Union to sign an agreement to limit the amount of strategic weapons that both countries could possess. In 1993, Doc hung a photograph of himself with Ford and Brezhnev in his chicken restaurant.

Jimmy Carter, the 39th president, was in office from 1977 to 1981. A poster for his presidential campaign was on the wall of the Blast from the Past antique shop in 2015.

In 1985, Ronald Reagan, the 40th president of the United States, was in office. In 1955, when Marty told Doc who the president was in 1985 (Reagan being an actor at the time), he scoffed at the idea and sarcastically asked whether Jane Wyman was the First Lady and Jack Benny was Secretary of the Treasury.

George H. W. Bush, the 41st president, was in office from 1989 to 1993. He was previously vice president under Ronald Reagan. In 2015, Doc Brown went into the Blast from the Past antique shop to try to find out the value of the items that he owned in 1985. While there, he saw a poster for the Reagan/Bush presidential campaign of 1984.

In the original 2015 timeline, there was a female president who, according to the Newsline column on the front page of the October 22, 2015 issue of USA Today, was tired of reporters asking her the same questions. However, she was only referred to as president, and not expressly as President of the United States, so it was possible she was president of another country, or of a company, in 2015.Existence of reality presidents between 1992 and 2008 (Bill Clinton and George W. Bush) is possible, but not confirmed.

When Doc traveled back in time to prevent a nuclear holocaust from occurring in 2045, most of the events that happened in 2015 in the original timeline did not come to pass. As a result, it's possible, but not confirmed, that Barack Obama was president during 2015, as he was in reality.

Donald Trump, the real-life inspiration for the 1985A incarnation of Biff Tannen according to Bob Gale, became the 45th president on January 20, 2017. Existence of reality presidents after 2020 (Joe Biden afterwards) is possible, but not confirmed.

The alternate Biff himself ran a campaign in 1986A to get elected president in 1988, but was ultimately killed upon being temporarily sent back to 1884.

Behind the scenes[]