Zohra Sehgal
From Tardis Wiki, the free Doctor Who reference
Zohra Sehgal (27 April 1912-10 July 2014)[1] played Sheyrah in the Doctor Who story The Crusade. She had previously had an uncredited role as Attendant to Ping-Cho in Marco Polo. (DWM 240) She was the first person associated with Doctor Who to reach the age of 100.
She passed away at 102 years old from cardiac arrest with the wish to be cremated, making Olaf Pooley the oldest living Doctor Who actor.