Caroline John

It was announced today that Third Doctor companion actress Caroline John has passed away. She died on 5th June, but her family held back the announcement until after yesterday's funeral.
Carry, as she liked to be called, joined the programme for Pertwee's first season, as Cambridge University scientist Dr Liz Shaw. She had only 4 adventures (3 of the stories of season 7 were 7 episodes each) and left before the next season. Producer Barry Letts was going to let her go, as he felt the character was too smart, almost an equal to the Doctor, and would not realistically be able to ask any of the questions which the audience might want answered - one of the companion's roles at that time.
Carry did not mind - as she was pregnant and was about to withdraw anyway. Sadly, the character was written out off screen, so we don't have a farewell to look back on.
She returned to the role twice - most notably as an apparition of her character in The Five Doctors. The other appearance was in the best forgotten Dimensions In Time skit for Children In Need.

The character was name-checked most recently in the Sarah Jane Adventures story Death of the Doctor, where we learned she had rejoined UNIT and was working at their base on the Moon.
Carry herself reprised the role in a couple of spin-off areas - a pipe-smoking version in a number of BBV videos (The P.R.O.B.E. series) and with Big Finish audios.
Her husband, Geoffrey Beevers, is also well known to Doctor Who audiences. He had a small role as a UNIT soldier in her story Ambassadors of Death and he returned in The Keeper of Traken as the deformed Master (a role he has continued with BF).
There is a Poirot episode (Problem At Sea) which features both as a couple.

Another piece of Doctor Who history gone - but never forgotten. She will probably be remembered best by fans for her dual role in Inferno - playing both Liz and the, initially nasty, parallel world Section-Leader Shaw.
Let's hope that the planned Special Edition release of this story pays due respect to her contribution to the series.