| 42121 | April 12 | Birth | 1944 – Lisa Jardine, English historian, author, and academic (d. 2015) |
| 42122 | April 12 | Birth | 1944 – John Kay, German-Canadian singer-songwriter, guitarist, and producer (The Sparrows and Steppenwolf) |
| 42123 | April 12 | Birth | 1945 – Lee Jong-wook, South Korean physician and diplomat (d. 2006) |
| 42124 | April 12 | Birth | 1946 – Ed O'Neill, American actor |
| 42125 | April 12 | Birth | 1946 – George Robertson, Baron Robertson of Port Ellen, Scottish politician and diplomat, 10th Secretary General of NATO |
| 42126 | April 12 | Birth | 1947 – Roy M. Anderson, English epidemiologist, zoologist, and academic |
| 42127 | April 12 | Birth | 1947 – Martin Brasier, English palaeontologist, biologist, and academic (d. 2014) |
| 42128 | April 12 | Birth | 1947 – Alex Briley, American singer (Village People) |
| 42129 | April 12 | Birth | 1947 – Tom Clancy, American historian and author (d. 2013) |
| 42130 | April 12 | Birth | 1947 – Woody Johnson, American businessman and philanthropist |
| 42131 | April 12 | Birth | 1947 – Dan Lauria, American actor |
| 42132 | April 12 | Birth | 1947 – David Letterman, American comedian, actor, and talk show host |
| 42133 | April 12 | Birth | 1947 – Wayne Northrop, American actor |
| 42134 | April 12 | Birth | 1948 – Jeremy Beadle, English television host and producer (d. 2008) |
| 42135 | April 12 | Birth | 1948 – Don Fernando, American porn actor and director |
| 42136 | April 12 | Birth | 1948 – Joschka Fischer, German academic and politician, Vice Chancellor of Germany |
| 42137 | April 12 | Birth | 1948 – Marcello Lippi, Italian footballer, manager, and coach |
| 42138 | April 12 | Birth | 1948 – Lois Reeves, American singer (Martha and the Vandellas) |
| 42139 | April 12 | Birth | 1949 – Scott Turow, American lawyer and author |
| 42140 | April 12 | Birth | 1950 – Flavio Briatore, Italian businessman |
| 42141 | April 12 | Birth | 1950 – David Cassidy, American singer-songwriter, guitarist, and actor |
| 42142 | April 12 | Birth | 1950 – Nick Sackman, English composer and educator |
| 42143 | April 12 | Birth | 1951 – Tom Noonan, American actor, director, and screenwriter |
| 42144 | April 12 | Birth | 1952 – Reuben Gant, American football player |
| 42145 | April 12 | Birth | 1952 – Gary Soto, American author and poet |
| 42146 | April 12 | Birth | 1952 – Ralph Wiley, American journalist (d. 2004) |
| 42147 | April 12 | Birth | 1953 – Tanino Liberatore, Italian author and illustrator |
| 42148 | April 12 | Birth | 1954 – John Faulkner, Australian educator and politician, 52nd Australian Minister for Defence |
| 42149 | April 12 | Birth | 1954 – Jon Krakauer, American mountaineer and author |
| 42150 | April 12 | Birth | 1954 – Steve Stevaert, Belgian businessman and politician, Governor of Limburg (d. 2015) |