The Doctor is the central role of the series. One of the things that makes Doctor Who successful is that each actor that portrays the Doctor brings with him his own take upon the role. No two doctors are alike; from the way they dress to their manerisms and behaviours. The response to danger, to the people around him, to events of the past and future are all redefined each time the Doctor changes.
Amongst so many great quotes, this really sums up what a new Doctor brings. "Trouble’s just the bits in-between! It’s all waiting out there, Jackie. And it’s brand new to me – all those planets and creatures and horizons! I haven’t seen them yet, not with these eyes. And it is gonna be fantastic."
One of the essential elements of Doctor Who are the companions he travels with. Most of his companions are humans from the present time of the given Doctor. The role of the companion has actually evolved with the run of the series. Initially the companions were more like audience surrogates; that is, the character who asks questions that the audience would want to know. With the revamp of the series though, the companions are more a driving element of the stories themselves.
Regardless of their role, the companion is someone that we can relate to and engage with while traveling through time and space. Said by Neil McNeil of Geek and Sundry, “I think the series has gone on for so long because it’s a new take on the fairytale genre, something that people can picture themselves being a part of. The show examines human existence while still bringing viewers to fantastic, faraway places they never could have imagined.” He credits the companions for the show's long run.
"Exterminate!" "Don't blink, blink and your dead." "You will be deleted." "Are you my mummy?" "Moisturize Me! Moisturize Me!" Just a few simple words yet, they express so much as many Doctor Who fans will immediately recognize the villian from just a simple phrase.
The world of Doctor Who has many well known antagonists. Whether it's the Dalek, the Cybermen or the Master; there is someone or something always waiting around the corner. Looking back at Classic Doctor Who, some of the Villians have undergone small changes, and others more drastic changes. None more so than The Master who has been portrayed by several different people. Some of the scariest and most sinster monsters have come more recently from the mind of Steven Mofat in the form of the Weeping Angels and the Silence.
The TARDIS which stands for Time And Relative Dimension In Space is a time and space machine which the Doctor and his companions use to travel in. The TARDIS isn't just a ship though. It possesses a degree of sapience and provides their users with additional tools and abilities including a universal translation system based on telepathy.
In the episode "The Doctor's Wife" the ships consciousness inhabits a human body. Narratively, this episode was important because it depicted the Doctors TARDIS in human form, and offered revelations about the relationship of the two time travellers.
In Classic Doctor Who, the Doctor also travels in a car effectionately known as Bessie.