"There are some corners of the universe which have bred the most terrible things. Things which act against everything we believe in. They must be fought."

The Second Doctor --
Patrick Troughton

The Second Doctor is a bit of whimsy compared to the First. Troughton played the part as a "cosmic hobo" who wasn't always the tower of strength the First Doctor was, but who still defeat an evil alien menace when he needed. If not on the first attempt then on the second.

Troughton's Doctor faced many old foes like the Daleks and the Cybermen, but he also encountered some new threats like the Yeti and the Ice Warriors. In fact, Troughton's time as the Doctor has been dubbed by some as the Moster Era because of the number of alien creatures the Second Doctor encountered.

It was also during Troughton's reign that the character of Colonel Alistair Gordon Lethbridge-Stewart, later to become Brigadier, was introduced and the agency known as UNIT was first seen.

Troughton had it twice as hard as any other Doctor. Not only did he have to follow in the footsteps of William Hartnell, but he had to convice everyone that he was the Doctor at a time when the idea of regeneration was unknown. But, Troughton took the part and made it his own.