Fernando Alonso - Renault
Succeeding Michael Schumacher, and becoming the only other driver to win a WDC title in the 21st century, was always going to be a monumental achievement fraught with pressure. Fernando Alonso not only broke Schumacher's streak of five straight WDC titles, he did so in classic Schumacher style - showing great maturity and composure to grind out the title on attrition.
Renault's emphasis on reliability rather than speed gave Alonso the appearance (at times) of cruising. Fortunately, the young Spaniard wrapped up the Championship with two races to go, and was able to follow his more natural and aggressive style at Suzuka and Shanghai. Without those two performances to correct misperceptions, the 'cruiser' label may well have stuck.
For the second time in three seasons, the young Finn challenged strongly for the title, only to fall agonizingly short. In 2003, he had reliability and consistency, but lacked the speed to win regularly. This year, it was the other way around. Raikkonen had awful luck with engine failures. But out of the bad luck came some good - that his seemingly hopeless Championship position freed him up to go for broke at every race.