William Russell

Sadly, William Russell—Ian Chesterton—has died at the age of 99: obituary from The Guardian. 

He had a long life, and he returned for a cameo a couple of years ago; I was thrilled to see him.

May he rest in peace. 

DW: "Boom"

Well, that was an episode for which the first two of the season really didn't prepare me. 

( spoilers )