Season Four is a must-have. The amazing Catherine Tate shows the world just how great it can really be when the Doctor has a companion who views him as an equal, not a love interest. The only series of all four to have episodes that brought tears to my eyes, and that would mostly be a testament to Catherine's Donna. New questions are started with the introduction of River Song, and old nagging questions answered as the Rose Tyler storyline is neatly, if a bit fan-indulgently, tied off (although nothing's ever set in stone when you have a Tardis I guess.)

Finally, now that the shadows are full of Vashta Nerada (sp??), I may never turn a light off again!

This is the most thrilling and exciting series yet. With the return of 2006's Donna Noble(Catherine Tate) this series is revealing, appealing and completely barmy!!! Davros, who has been seen through Doctor Who episodes since his first appearance in the 1970's, makes a spectacular return to the series in the stand-off finale, along with Rose Tyler(Billie Piper) Sarah Jane Smith(Elisabeth Sladen) Martha Jones(Freema Agyeman) and Captain Jack(John Barrowman) this series is the one for you!!!

Series four saw the Doctor and Donna Noble (David Tennant and Catherine Tate) united at last, after their first meeting in ‘The Runaway Bride’ (series three's Christmas special).

From the opening episode, ‘Partners in Crime’ to the heart-wrenching finale, ‘Journey's End’, we caught glimpse of an alternate version of Earth, the future, and even the past (where we discovered what part the Doctor & Donna played in the disappearance of Agatha Christie).

Donna was, perhaps, the best companion we've seen in the series to date. Her interactions with not only the Doctor (who seemed to brood much more this season than he has in previous ones – not that you'll hear any complaints about that from me!), but previous companions and friends also (Martha and Rose, and the ever flirtatious Jack Harkness, to name but a few), were well written and well played by Catherine Tate.

David Tennant seemed to be at his best this season, playing a range of emotions, and playing them -very- well.

Of course, one can't forget ‘Voyage of the Damned’, a particularly spectacular Christmas special with none other than Kylie Minogue as his companion. The special effects, storyline, and acting were top notch, and a perfect interlude between series three and four. Let's hope we get to see Kylie's character again sometime in the future…after all, it's Doctor Who, anything is possible :)