5 March 1932: birth of Gertan Kauber, who played the dimly seen galley-master in the story we now call The Romans (First Doctor, 1965) and Ola in The Macra Terror (Second Doctor, 1967)
5 March 1972: birth of James Moran, writer of The Fires of Pompeii (Tenth Doctor, 2008) and the Torchwood episode Sleeper (2008); co-writer of Torchwood: Children of Earth: Day Three (2009).
5 March 1974: birth of Matt Lucas, who played Nardole in the Twelfth Doctor era.
5 March 2012: death of Philip Madoc, who was Brockley in Daleks - Invasion Earth 2150 AD (Movie 1966), Eelek in The Krotons (Second Doctor, 1968-9), the War Lord in The War Games (Second Doctor, 1969), Solon in The Brain of Morbius (Fourth Doctor, 1976), and Fenner in The Power of Kroll (Fourth Doctor, 1978-9).
ii) broadcast anniversaries
5 March 1966: broadcast of "The Steel Sky", first episode of the story we now call The Ark. The Tardis lands on a vast spaceship inhabited by humans and Monoids; Dodo's cold spreads throughout its inhabitants. First full episode with Dodo, for whom I have an obscure affection.
5 March 1979: broadcast of second episode of The Talons of Weng-Chiang. The Doctor and Jago find a ghost at the theatre; Leela and Litefoot find Mr Sin at the door.
5 March 2008: broadcast of Something Borrowed (Torchwood), the one where Gwen gets married despite an alien pregnancy.
iii) date specified in-universe
5 March 2005: death of Clara Oswald's mother Ellie.