| 142351 | December 18 | Event | 1932 – The Chicago Bears defeat the Portsmouth Spartans in the first NFL Championship Game. |
| 142352 | December 18 | Event | 1935 – The Lanka Sama Samaja Party is founded in Ceylon. |
| 142353 | December 18 | Event | 1939 – World War II: The Battle of the Heligoland Bight, the first major air battle of the war, takes place. |
| 142354 | December 18 | Event | 1944 – World War II: Seventy-seven B-29 Superfortress and 200 other aircraft of U.S. Fourteenth Air Force bomb Hankow, China, a Japanese supply base. |
| 142355 | December 18 | Event | 1956 – Japan joins the United Nations. |
| 142356 | December 18 | Event | 1958 – Project SCORE, the world's first communications satellite, is launched. |
| 142357 | December 18 | Event | 1966 – Saturn's moon Epimetheus is discovered by Richard L. Walker. |
| 142358 | December 18 | Event | 1969 – Capital punishment in the United Kingdom: Home Secretary James Callaghan's motion to make permanent the Murder (Abolition of Death Penalty) Act 1965, which had temporarily suspended capital punishment in England, Wales and Scotland for murder (but |
| 142359 | December 18 | Event | 1971 – Capitol Reef National Park is established in Utah. |
| 142360 | December 18 | Event | 1972 – Vietnam War: President Richard Nixon announces that the United States will engage North Vietnam in Operation Linebacker II, a series of Christmas bombings, after peace talks collapsed with North Vietnam on the 13th. |
| 142361 | December 18 | Event | 1973 – Soviet Soyuz Programme: Soyuz 13, crewed by cosmonauts Valentin Lebedev and Pyotr Klimuk, is launched from Baikonur in the Soviet Union. |
| 142362 | December 18 | Event | 1973 – The Islamic Development Bank is founded. |
| 142363 | December 18 | Event | 1978 – Dominica joins the United Nations. |
| 142364 | December 18 | Event | 1987 – Larry Wall releases the first version of the Perl programming language. |
| 142365 | December 18 | Event | 1989 – The European Economic Community and the Soviet Union sign an agreement on trade and commercial and economic cooperation. |
| 142366 | December 18 | Event | 1997 – HTML 4.0 is published by the World Wide Web Consortium. |
| 142367 | December 18 | Event | 1999 – NASA launches into orbit the Terra platform carrying five Earth Observation instruments, including ASTER, CERES, MISR, MODIS and MOPITT. |
| 142368 | December 18 | Event | 2002 – 2003 California recall: Then Governor of California Gray Davis announces that the state would face a record budget deficit of $35 billion, roughly double the figure reported during his reelection campaign one month earlier. |
| 142369 | December 18 | Event | 2005 – The Chadian Civil War begins when rebel groups, allegedly backed by neighbouring Sudan, launch an attack in Adré. |
| 142370 | December 18 | Event | 2006 – The first of a series of floods strikes Malaysia. The death toll of all flooding is at least 118, with over 400,000 people displaced. |
| 142371 | December 18 | Event | 2006 – United Arab Emirates holds its first-ever elections. |
| 142372 | December 18 | Birth | 1507 – Ōuchi Yoshitaka, Japanese daimyo (d. 1551) |
| 142373 | December 18 | Birth | 1602 – Simonds d'Ewes, English historian and politician (d. 1650) |
| 142374 | December 18 | Birth | 1610 – Charles du Fresne, sieur du Cange, French philologist and historian (d. 1688) |
| 142375 | December 18 | Birth | 1620 – Heinrich Roth, German missionary and scholar (d. 1668) |
| 142376 | December 18 | Birth | 1626 – Christina, Queen of Sweden (d. 1689) |
| 142377 | December 18 | Birth | 1660 – Countess Johanna Magdalene of Hanau-Lichtenberg (d. 1715) |
| 142378 | December 18 | Birth | 1661 – Christopher Polhem, Swedish physicist and inventor (d. 1751) |
| 142379 | December 18 | Birth | 1662 – James Douglas, 2nd Duke of Queensberry, Scottish colonel and politician, Secretary of State for Scotland (d. 1711) |
| 142380 | December 18 | Birth | 1707 – Charles Wesley, English missionary and composer (d. 1788) |