Hello there! Grab yer jelly babies and decorative scarf as my countdown to Doctor Who's fiftieth anniversary this month means the Fourth Doctor. The definitive article, you might say.
The Doctor (Tom Baker)
For so many, Tom Baker is Doctor Who.
Throughout his seven year tenure as everyone's favourite Time Lord (the longest of any actor) a generation fell in love with his loopy, man-child, really alien version of the Doctor. His trademarks; hat, longcoat, scarf, wide grin and seemingly-bottomless bag of jelly babies have firmly seeped into popular culture - his image appearing in such shows as the Simpsons. Every Doctor since has Tom Baker's shadow over them, the public wondering if they will ever reach the Fourth Doctor's popularity. Arguably, no one quite has.
In great contrast to his Earth-bound predecessor, the Fourth Doctor hated being tied to one place and working with authority. As soon as he got the chance he leaves his job at UNIT to roam freely round the universe. Extremely charismatic and able to laugh in the face of danger, the Fourth Doctor often took control of situations without anyone realising or minding and fought evil with a smile on his face. Not that this was all a joke. When given the opportunity to stop the Dalek's from ever existing, the weight and responsibility of such a challenge hits home and the Doctor has to solve a moral dilemma. However, perhaps the Fourth Doctor's defining characteristic is his completely alien nature. Utterly unpredictable, companions and viewers alike had no idea what this Doctor would do when, for instance, he became swayed by the universe-conquering power of the Key to Time he held in his hands or his callousness once at seeing a dead body. In episodes set in his home world, you'll see he's even more alien than his fellow Gallifreyans. He's one of a kind. The Madman with a box.
The Fourth Doctor travelled with a several dear friends - perhaps forming the closest relationships with a companion the Doctor had up to that point. Inherited from the Third Doctor, Sarah Jane Smith was, in his own words, the Doctor's 'best friend.' Along with UNIT Doctor Harry Sullivan, they enjoyed some of Doctor Who's greatest adventures together before Harry returned to his job and the Doctor was summoned to Gallifrey - where humans could not go - and forced to leave Sarah behind. She would go on to be one of the show's most beloved characters. Warrior girl Leela of the Sevateem accompanied the Doctor next, as did robot dog K-9 - of whom four versions exist, gifts to different companions. Icy Time Lady Romana was the first companion to be the Doctor's equal - someone who didn't need things explained to her all the time. Shortly before his death at the hands of the Master, he met maths-whizz Adric, alien noblewoman Nyssa and mouthy air hostess Tegan.
On the whole, the Fourth Doctor's tenure is often cited as the finest era of the show. Featuring many classic stories and some of fans most favourite companions and monsters, it was always going to be good. However, the casting of Tom Baker in the lead pushed the show the extra length. Quite simply, the Fourth Doctor changed Doctor Who forever.