1961

April

 * 12 - Yuri Gagarin of the Soviet Union became the first human to travel into space, at least officially. (AUDIO: Thin Ice)

Unknown dates

 * UNIT's predecessor, Great Britain's Intrusion Countermeasures Group, was formed. Its leader, Group Captain Ian Gilmore, began training his men. (PROSE: Who Killed Kennedy)
 * Peter Tracey was born. (TV: A Girl's Best Friend)
 * Allison Williams and Julian St. Stephen started dating. (AUDIO: Artificial Intelligence)

Alternative timeline

 * In an alternative timeline in which Nazi Germany won World War II as a result of the Seventh Doctor and Ace accidentally leaving laser technology in Colditz Castle in October 1944, the Führer Adolf Hitler died at the age of 71 or 72. Prior to his death, he had stockpiled a large number of alien artefacts including the TARDIS but had kept them contained because he had feared the implications of intelligence superior to humans. (AUDIO: Klein's Story)

January

 * 7 - debuted on British television. The series was devised by Sydney Newman, who next went on to create Doctor Who. During its run (which would last until 1969), the series played host to many guest actors who also appeared on Doctor Who, and many Doctor Who scriptwriters also wrote for The Avengers, including Terrance Dicks and Malcolm Hulke.
 * 12 - Actor Sean Blowers was born.

February

 * 19 - Actor Susan Baker was born.

April

 * 3 - Actor Edward Highmore was born.
 * 23 - Comic penciller Art Wetherell was born.
 * 25 - Actor Cyril Nri was born in Nigeria.

May

 * 17 - Actor Corey Johnson was born in America.
 * 20 - Actor Owen Teale was born.
 * 28 - Actor Michelle Collins was born.

June

 * 27 - Actor Meera Syal was born.

September

 * 7 - Actor Jamie Bradley was born.

October

 * 3 - debuted on the BBC. This seven-part science fiction serial was considered a prime inspiration for the BBC considering the development of an ongoing serialised science fiction series which eventually became Doctor Who.
 * 26 - Actor Sakuntala Ramanee was born.
 * 31 - Actor Moya Brady was born.

November

 * 18 - Head writer Steven Moffat was born.
 * 28 - Actor Martin Clunes was born.

December

 * 6 - Actor Robin Aspland was born.
 * 12 - Actor Sarah Sutton was born.
 * 19 - Actor Matthew Waterhouse was born.

Unknown dates

 * Writer David J. Howe was born.