Elisabeth Claira Heath Sladen (Miller) 1946-2011

We learned yesterday of the passing of actress Elisabeth Sladen, best known as Sarah Jane Smith on Doctor Who and The Sarah Jane Adventures, due to cancer.

with the Third Doctor (Jon Pertwee)

She played opposite Jon Pertwee, then Tom Baker as The Doctor.
Elizabeth was so popular that, when she left the show, it drew media attention that only the changing of the Doctor's portrayers had previously-garnered.

with the Fourth Doctor (Tom Baker)

The BBC created a pilot called K-9 & Company starring Sladen as Sarah Jane along with the robot dog created during Baker's run of Dr Who.
It wasn't picked up, but Elizabeth returned to the Sarah Jane role in "The Five Doctors", playing opposite Jon Pertwee once more as all The Doctor's incarnations (along with various aides) were brought to Galifrey, his home planet.

Elizabeth played Sarah Jane once more on the resurrected Doctor Who (the first human character from the earlier series to do so) in "School Reunion".

with the Tenth Doctor (David Tennant)

with the Eleventh (current) Doctor (Matt Smith)

With both ratings and audience response to Sarah Jane's return going thru the roof, the BBC decided to add a second Dr Who spinoff, but with a juvenile slant, to counterpoint TorchWood's more "adult" orientation.
The result was The Sarah Jane Adventures, with Elizabeth leading a motley group of teens, including Sarah Jane's adopted son, against alien threats to Earth.
The series, now in it's fifth year, is among the highest-rated kids' shows in England.

Hopefully, SyFy will run the remaining seasons of Sarah Jane Adventures...