Doctor Emmett L. "Doc" Brown is a fictional character central to the Back to the Future movies created by Robert Zemeckis and Bob Gale. Doc Brown, who was portrayed by Christopher Lloyd, is the inventor of the De Lorean time machine in which he and his friend Marty McFly travel through time. Emmett L. Brown was born in 1920 in Hill Valley, California and at age 11 discovered the works of Jules Verne. This led him into a career in science, and in 1955 he came up with the idea of the flux capacitor after slipping from his toilet and bumping his head. The flux capacitor is what makes time travel possible. The time machine suffered a setback on August 1st 1962 when Doc's mansion burnt down, but he was soon back on track and on May 23rd 1983, he was commended and won an award.

Doc finally finished installing his time machine in a DeLorean sports car in 1985, using plutonium to power it, and was killed by the Libyan terrorists who had given it to him. In return they had wanted a bomb, and he had made a non-working one out of used pinball machine parts. Fortunately, Doc's friend Marty McFly was accidentally sent back to 1955, where he warned Doc about the terrorists. When 1985 rolled around again, Doc wore a bulletproof vest for protection.

Doc and Marty have embarked on a series of adventures to 1955, 2015, an alternate 1985, and 1955 again where the De Lorean, with Doc inside, got struck by lightning and was accidentally sent back to 1885. It was here that Doc met his future wife, Clara Clayton, whom he now currently resides with in the Old West with their two sons Jules and Verne and uses a modified train locomotive with a time travel function.

His attitudes towards maintaining history vary during the trilogy. In the second film, he thinks that the time machine poses a threat to the fabric of time and should be destroyed, regardless of the knowledge it can bring or the good it can do. By the end of the third film, Doc has changed his opinion on the matter and created a second time machine, which he uses to travel to 1985 and at least one unspecified time in the future.

Although Doc is extremely intelligent, he is rather absent-minded at times. He cheated Libyan terrorists without preparing for their inevitable retribution, and would have died as a result had not Marty intervened. He referred to the time machine as a time machine in public, leading Biff Tannen to use it without Doc's knowledge in an attempt to alter history. In 1985, he flew land-based vehicles with hover conversions during the daytime, with no consideration of the possibility of people seeing him.

According to Robert Zemeckis, there was a strong implication that Doc Brown had worked on the Manhattan Project, although this was never explicitly stated in the film trilogy.