Doctor Who: Two
The Second Doctor: Patrick TroughtonWhen the time came for William Hartnell to retire and a Second Doctor to be cast, the Doctor Who production team made some very interesting choices. What they did was not look for an actor who had a track record of playing characters like the Doctor they wanted, but an actor who was in many ways was the Doctor they wanted, and had a track record of playing larger than life without making the audience want to throw tomatoes at the TV. This has resulted in a lot of actors being cast blatantly against type, but in exchange, almost all of them have remained very fond of the franchise even after leaving.
First Serial: The Power of the Daleks
Last Serial: The War Games
Costume: Cheerful space hobo-clown. Black sack coat, baggy checked trousers, bow tie, Moe Howard haircut. Be sure to leave room in the interior breast pocket for a tasseled recorder.
Companions: Polly, Ben Jackson, Jamie MacCrimmon, Victoria Waterfield, Zoe (honorable mention: Brigadier Col. Alastair Gordon Lethbridge-Stewart, Sgt. Benton)
Prior to DW, Patrick Troughton was known mainly for horror movies, as he had the sort of face that looked terrifying when lit from beneath with a flashlight. In real life, he was rather cheery and something of a prankster. Troughton was notorious for pranks, like the time he went for his handkerchief and instead pulled a pair of frilly ladies' knickers out of his breast pocket -- I don't know what the lead up to that one was, but it ended with poor Deborah Watling wailing, "But they're not mine!" and apparently none of them have ever forgotten it. His Doctor was more or less himself, only without his glasses, and with his pleasant daffiness turned up to eleven.
The Second Doctor is unfortunately one of the least-known, mainly because his stories compose the lion's share of the fabled "lost episodes". It was right about here, however, that DW started to attain cult status, and a remarkable number of people attached to the production back then have remained enthusiastic participants in the franchise and in the fan culture since. (From the First Doctor's time, Carole Ann Ford does occasionally turn up to things when asked, and Peter Purves was a long-time presenter for Blue Peter, a British children's show that's fond of spotlighting DW, but other than that, the participants were generally bit-parters or actors who went on to do things for which they became much more prominent.) Frazer Hines in particular has done quite a lot over the years, from conventions to narrating audiobooks or linking narration to cover missing episodes from some of his serials, all the way to standing in as the voice of the Second Doctor in a just-released Big Finish Audio, "The Light At The End". He does quite an uncanny imitation of Troughton -- who himself passed away in the '80s while attending a Doctor Who convention.
Of note continuity-wise, is that although they were not officially companions until the Third Doctor's appearance, the Second Doctor was the first to work with Alastair Gordon Lethbridge-Stewart (aka the Brigadier) and his aide, Sergeant Benton. The Brig, played by Nicholas Courtney, is canonically the only character to have met every Doctor so far, in one medium or another -- save possibly Eleven, but I haven't combed through everything to check. He's prone to asking 'which one are you?' whenever he runs into another one -- for what it's worth, the Doctor answers with ordinals, so he does keep track -- and politely refrains from telling the Doctor too much of his own future.
The Second Doctor is also notable for the mention he gets from some of his future incarnations. Peter Davison was the first Doctor young enough to have watched the program when he was young, and cites Troughton as his inspiration; more recently, Matt Smith declared the same, and the geeky bow tie is at least partly an homage to Troughton's.
The Doctor's first real troubles with the other Time Lords date from the Second; it's made quite clear during his time that he stole the TARDIS and ran, his people are not happy with him, and that in fact he's trying like hell to not ever, ever, ever have to go home, because he doesn't like it there. (The First Doctor tangled briefly with the Mad Monk, but the Monk was a fugitive like he was -- neither of them were going to alert the authorities if they could help it.) Gallifrey does eventually catch up with him at the end of "The War Games", where they forcibly separate him from his human pets, dump them back in their own times without any memory of their adventures together, take an important part out of the TARDIS, and then huck the Doctor and his broken box back into present-day England, taking one of his regenerations as they go.
The Doctor versus one of his least favorite beings in the universe.
"I was bored!"
Farewell to Zoe and Jamie.