12 May 1968: birth of Catherine Tate, who played Donna Noble in New Who from 2006 to 2010.
12 May 2001: death of Norman Kay, who composed the incidental music for An Unearthly Child (1963), The Keys of Marinus (1964) and The Sensorites (1964).
ii) broadcast anniversaries
12 May 1973: broadcast of sixth episode of Planet of the Daleks. The Doctor, Jo and the Thals trap the Daleks in the ice volcano.
12 May 1996: first broadcast of Doctor Who: The Movie on a local cable channel in Edmonton, Canada.
12 May 2007: no Doctor Who episode shown today, the series taking a break for the Eurovision Song contest between The Lazarus Experiment and 42.
iii) date specified in canon
12 May 1999: birth of Adelaide Brooke, who we meet in The Waters of Mars (2009).