Ronald Reagan

Ronald Reagan served as the President of the United States in the 1980s. He had been an actor and the Governor of California prior to his presidency. According to the Eighth Doctor, he served between Jimmy Carter and Bill Clinton. (PROSE: Interference - Book One) According to one account, in 1998 President Tom Dering once said that either Reagan or Carter secretly constructed Station Nine. (PROSE: Option Lock)

Joel Mintz's father fixed up the 1950s nuclear shelter in their backyard after Reagan was elected. He made his wife and Joel do drills to get into the shelter in under a minute. (PROSE: Return of the Living Dad)

By 28 February 1981, President Reagan's administration decided the Cold War needed some "hotting up". It planned to end "skulking and stockpiling" to prove the United States would not be intimidated and to test the boundaries of the USSR. (PROSE: Nuclear Time)

On 30 March 1981, he was the victim of an assassination attempt by John Hinckley Jr. He received a bullet in his lung. (PROSE: The Assassin's Story) Bernice Summerfield noted that even this would not make him budge. (PROSE: The Left-Handed Hummingbird)

The Reagan administration was invested in Christian Fundamentalism and the "Star Wars" program. (PROSE: Heart of TARDIS)

Peri Brown figured that the people on Reef Station One in the 101st century who were nostalgic about the 20th and early 21st centuries had never heard of AIDS, Ethiopia or Ronald Reagan. (PROSE: Synthespians™)

Helen Sinclair taught Robin Bright-Thompson about Reagan and Mikhail Gorbachev. He had a feeling, however, that she was "winging it", a suspicion that was confirmed when he learnt that she was from 1963. (AUDIO: Dead Time)

Alternate timeline
In an alternate timeline, Anna described the idea of Reagan being President of the United States as ridiculous. (AUDIO: Red Planets)

Information from non-valid sources

 * "Ronnie" was one of the panellists on the same game show as the one on which the Sixth Doctor and Peri Brown appeared during their eighteen month holiday. They were also joined by Ena Sharples, Adolf Hitler and Attila the Hun. (NOTVALID: Doctor Who? 110)