Second Doctor

Played by Patrick Troughton throughout, the Second Doctor holds a special place in my Whovian heart due to a number of firsts:

• First serial I watched: The Mind Robber (1992 repeat).
• First serial I rented: The Seeds of Death (back when video renting was a thing).
• First serial I purchased: The Tomb of the Cybermen (from Boots, VHS format).

Troughton arguably had the hardest role ever, in that his performance would decide whether the regeneration concept, and the resulting change of lead actor, would be a success. If he had failed to convince viewers that he was still the Doctor, albeit with a different (and in my opinion, greatly improved) persona, then the show may never have made it beyond Season Five.