the BBC 's new production of its classic series , Doctor who , weather its first major casting change admirably . most actor remain in the lead role for at least three year , but for Christopher Eccleston , one year be enough , and he doctor -lrb- aka ` nine ' -rrb- die in the season one finale . in keep with who tradition , the Doctor , upon he death , regenerate into a completely new body . take the TARDIS control from Eccleston be another Russell t Davies alumnus , David Tennant -lrb- who headline Davies ' production of casanova -rrb- as the tenth incarnation of the doctor -lrb- aka ` ten ' -rrb- . Tennant have he work cut out for he , follow Eccleston 's marvelous turn as the Time Lord , but he make the transition so seamlessly that the character truly seem like the same man in a different body . aid this transition be largely the same writing and production staff , as well as the same co-star -lrb- Billie Piper as Rose Tyler -rrb- and support cast -lrb- Camille Coduri as Jackie Tyler and Noel Clarke as Mickey Smith -rrb- . it be to Tennant 's credit that he not only immediately put he own stamp on the character but maintain Eccleston 's level of chemistry with the support cast . ten be physically younger than nine , more brash , more impulsive , less torment by guilt , but still achingly lonely . he loneliness become a run theme throughout the season , touch on in nearly every episode . Eccleston play the doctor as he play Steve Baxter in Davies ' the second coming -lrb- a tormented otherworldly be -rrb- ; Tennant play the doctor as casanova -lrb- a young , lovelorn romantic hero -rrb- . the Doctor 's romantic attachment , in fact , become the vehicle by which Davies explore the central theme of loneliness . ten and Rose build upon and deepen the romance that nine and Rose begin in the first season . they love be palpable ; they be often literally willing to die for each other . in the UK , the series be family-oriented and rarely stray beyond the pg level , so this romance be never physically consummate ; the character do not even kiss . despite this -- in fact , because of it -- they feeling be all the more poignant . -lrb- and how often do we see a depiction of true and abide love on television that do not involve some kind of bump-and-grind ? -rrb- by the end of the season , the relationship have come full circle : the Doctor have teach Rose all he can ; it be time for she to leave he and put to use all the thing she be learn . they final separation be tragic but yet also hopeful : despite the sadness , the viewer know Rose will thrive in she new environment . Billie Piper 's send-off could not have be more positive or more lovingly write -lrb- and it leave open the possibility of she return to the series in the future for a guest spot -rrb- . nobody who leave who be ever truly go . the tremendous `` School Reunion '' bring back a old fan favorite , Sarah Jane Smith -lrb- Elisabeth Sladen -rrb- . again , romance be the means by which Davies explore the Doctor 's impact on he companion ' life . the story be beautifully write : suspenseful , funny , romantic , and poignant . Sladen slip back into the role effortlessly , and Anthony Stewart Head provide a wonderful villain in the sinister Mr. Finch . romance also infuse the imaginative `` Girl in the Fireplace , '' in which a army of clockwork repair droid from the fifty-first century stalk Madame de Pompadour -lrb- Sopia Myles -rrb- . the doctor be clearly smite with the young Reinette , but the episode 's conclusion showcase how the heartbreakingly short human lifespan will always thwart such attachment . but romance be not all the second season have to offer : old foe return -lrb- Daleks , Cybermen , Cassandra -rrb- as well as old friend -lrb- Harriet Jones , Sarah Jane , K-9 , Pete Tyler , the Face of Boe -rrb- . also , the setting finally get away from Earth for a few episode , and there be a couple of trip to Earth 's past . the recur character develop beautifully , especially Mickey Smith , who finally come into he own as a hero . particularly good be the two-part story `` the impossible planet '' \/ `` the Satan pit , '' which find the doctor and Rose in a bleak space station on a planet perpetually circle a black hole . but the real standout of the season might well be `` the Christmas Invasion , '' a hour-long special that air on Christmas day , 2005 . this episode allow the support character -- and by extension the viewer -- a opportunity to adjust to the new doctor , and it allow ten to establish he heroic bona fide . the guest cast be marvelous , particularly Penelope Wilton as the UK 's new prime minister , Harriet Jones . a argument between the PM and ten at the episode 's conclusion be brilliant , worthy of the West wing , show that Davies be not afraid to challenge he viewer ' perception of heroism and villainy . other highlight of the season be `` the rise of the Cybermen '' \/ `` the age of Steel , '' the chill `` Tooth and Claw , '' the off-beat `` love and monster , '' and of course , the brilliant finale , `` Army of Ghosts '' \/ `` Doomsday . '' of all the episode , only the disjointed `` fear she '' feel sub-par . the overall quality of the season be remarkable , give the amount of backstage shuffling that take place -lrb- e.g. , the timing of Piper 's departure be initially unclear ; a few episode undergo last-minute rewrite -rrb- . and yet another challenge loom ahead for Davies as he reinvent the show in the wake of `` Doomsday , '' which write out literally the entire support cast . only two season in , and a era have already end . much of the season 's success be owe to Tennant , who have quickly establish himself as one of the most popular doctor in the show 's long history . he own love for the series and the character shine through every moment he be on scene , and he effortlessly convey the Doctor 's past through he expression , body language , and vocal inflection . if Eccleston be `` Doctor Modern , '' Tennant be `` Doctor Classic-Modern , '' meld perfectly the older and more contemporary portrayal of the character . he chemistry with Piper be nothing short of magical , and he also play wonderfully off the supporting and guest actor . as with the first season , the second season be best view in pristine dvd rather than the hacked-up version show on tv . the boxed set include the usual extra ; viewer should make the Pudsey Cutaway \/ Children in Need special they first stop -- it be a essential prologue to `` the Christmas Invasion . '' season two be proof positive that Doctor who can hold its own with pretty much anything else currently on television .