The Nightmare Begins was aired in November 1965 while Devil’s Planet was broadcast two weeks later.
The intervening episode, Day of Armageddon, was found in 2004 by a former BBC engineer, meaning fans now have the first three instalments of the series.
Written by the creator of the Daleks, Terry Nation, and Dennis Spooner, the serial starred Hartnell and Peter Purves as the Doctor’s assistant Steven Taylor, alongside an early appearance by Nicholas Courtney as Bret Vyon, Adrienne Hill as Katarina, and Kevin Stoney as Mavic.
Courtney would go on to play recurring character, The Brigadier, but the “dark and gritty” 12-part storyline was ordered to be wiped, and more than half of it remains missing.
Purves, 87, was invited to Phoenix Cinema in Leicester in March under false pretences to view the two recently found episodes.
After viewing them, he said: “My flabber has never been so gasted.”
At the time, Noreen Adams, director of BBC Archives, said she was “thrilled” the episodes would be released on BBC iPlayer.
They will be added to a raft of Doctor Who programming which forms The Whoniverse on BBC iPlayer.