I believe the traditional answer is "Splendid chaps, all of them."
—David Tennant when asked which Doctor was his favourite, Comic-Con 2009.
A Lothian-born bloke, David Tennant was born David MacDonald, but had to adopt a screen name for guild reasons (the "Tennant" coming from the last name of Neil Tennant of Pet Shop Boys). Best known for being The Tenth Doctor, as well as the lead role in a Casanova miniseries. In Harry Potter and the Goblet of Fire, his character is played by Brendan Gleeson for most of the movie, but Tennant does get a few scenes to display his..."eager" face (his face is wonderfully expressive, as you can see in any of his TV or film work). Played "Dangerous Beans" in a BBC radio adaptation of the Discworld novel The Amazing Maurice And His Educated Rodents. Did manage to get a role as a very convincing pre-op transsexual on Rab C. Nesbitt. Has auditioned 14 times for Taggart and failed each time.
In 2008, he played the eponymous character in the Great Performances production of Hamlet from the Royal Shakespeare Company alongside Patrick Stewart. The film adaptation can be viewed on PBS' website. In 2011, he played Benedick opposite Catherine Tate in a production of Much Ado About Nothing.
Tennant is also a Promoted Fanboy. A Doctor Who fan since childhood, he specifically went into acting to play the Doctor (in a strange case of irony, his first big role was in something called Takin Over the Asylum) and has shown himself to be quite knowledgeable about the history of the series in interviews. His Doctor is now rated among the top two of the eleven canon Doctors and he is now regularly winning "Best Doctor" polls.
Contrary to an infamous question on The Million-Pound Drop, he's not the longest-running Doctor. Hell, he doesn't even crack the top three.
He left Who after the 2009 specials. When he initially announced his departure at the National Television Awards, the fangirl (and fanboy) screams shattered glass fifty miles away.
He's married to Georgia Moffett (and has a child with her, Olive), who not only played his Opposite Gender Clone in "The Doctor's Daughter" but is also ex-Doctor Peter Davison's real-life daughter. (And guess who one of Tennant's favorite Doctors is? Right in one. David Tennant is now the ultimate Promoted Fanboy.) Sorry, ladies (and gentlemen).
Tennant is also the current host for Masterpiece Contemporary.
He is a public supporter of the Labour Party, delivering a very scathing criticism of David Cameron in early 2010 as well as providing the voiceover for Labour's 2010 Election Broadcast, although he avoided political commentary during his tenure as the Doctor because he felt it was improper. In 2011, he played showy vampire slayer Peter Vincent in the Fright Night remake.
- Adorkable: Yes. His foreword to the Doctor Who Specials boxset is heart-meltingly sweet.
- Ascended Fanboy: Grew up watching Doctor Who, became an actor to play the Doctor, became one of the most popular Doctors, got to work with one of his favorite Doctors (Peter Davison), and had a kid with and married (in that order) Davison's daughter.
- Cast Incest: While playing the Doctor, he fell in love with (and is now married to) the actress who played the Doctor's daughter. And now they have a daughter. As noted above, for extra bonus points Miss Moffett is the real-life daughter of Peter Davison. (Start thinking too hard about how the Actor Allusion works out and you may wind up in My Own Grampa territory.)
- Curtains Match the Window
- Defictionalization: Due to the tenth Doctor lighting the cauldron for the London 2012 Olympics in the episode "Fear Her," there have been online petitions to have Tennant light it for real. (Such as this one.)
- It's come about halfway true. The fans possibly did have something to do with The Doctor actually carrying the Olympic torch, but it was the current one and he only ran for one leg of it in Cardiff instead of actually lighting the flame in London, but the possibility is still out there.
- Geek Physique: During Who, both Donna Noble and the Fifth Doctor called him skinny boy at some point (well, Five called him "skinny idiot", but it still applies). He is pretty slim.
- Hot Dad: As of late March 2011. Played one in Single Father too.
- Identical Stranger: Has been compaired to Richard Hammond.
- Large Ham: THE LAWS OF TIME ARE HIS! AND THEY WILL OBEY HIM!!!
- Locked Out of the Loop: When the mysterious (and very important) character River Song first showed up in Doctor Who, Steven Moffat refused to tell anyone who she was. The Doctor's confusion is absolutely genuine.
- Mean Character, Nice Actor: Though best known for playing a heroic Time Lord, he was also a Death Eater. The sheer contrast between the homicidal lunacy of Barty Crouch Jr. and his adorkable and cuddly interview at the Goblet of Fire premiere is a sight to behold.
- Meaningful Name: David TEN-nant was Doctor TEN, and apparently nicknamed David Ten-Inch by Billie Piper.
- Older Than They Look: Would you believe he's 40?
- One of Us: Being a Promoted Fanboy of Who, this is to be expected. Also visible in his video diary footage are Star Wars figures and The West Wing DVDs. He also said he was a fan of Firefly and Serenity at Comic-Con, unfortunately at the same time as denying that his long brown coat was a deliberate reference to them.
- Promoted Fanboy: Let's count the ways.
- Grew up a huge fan of the Doctor, and got into acting specifically to play him.
- Was a big fan of Sarah Jane Smith (of course, who isn't?); got to work with Elisabeth Sladen in "School Reunion" and "The Wedding of Sarah Jane Smith", and was able to give Sarah Jane the "goodbye" from the Doctor she's been waiting decades for. Then was asked to write the foreword to Sladen's autobiography after her untimely death in 2011.
- Was a big fan of the Fifth Doctor, and got the chance to work with Peter Davison (as the Fifth Doctor) in the special "Time Crash".
- Furthermore, now that he's married to Davison's daughter Georgia Moffett, not only is he Davison's fan, he's also his son-in-law. Someone give him the Promoted Fanboy crown, please.
- Puppy Dog Eyes
- Purely Aesthetic Glasses: Giving his incarnation of the Doctor these was his idea, in order to provide a hero for children with glasses.
- Shakespearian Actors: He was an RSC man (including a well-regarded Romeo) before his stint in the TARDIS as the Tenth Doctor in Doctor Who, and moonlighted as a critically-acclaimed Hamlet between filming the 2009 specials. He's also played Benedick opposite Catherine Tate in Much Ado About Nothing.
- Squee: Tends to get this reaction a lot from his hordes of fangirls (and John Barrowman, when David kissed him at a con). As for David himself, he did this as a in- and out-of-universe version as the Tenth Doctor/himself to the Fifth Doctor/Peter Davison in "Time Crash".
- You can hear the fanboying in his head when he meets Elisabeth Sladen as Sarah Jane as the Doctor in "School Reunion".
- Tall, Dark and Handsome: 6' 1.
- Unkempt Beauty
- Vitriolic Best Buds: He and Catherine Tate have been good friends in real life (since they first met while filming the Doctor Who Christmas Special in 2006), and have done various shows together (Aside from Who, they've done a few one-off Catherine Tate Show charity skits together and a theater run of Much Ado About Nothing in 2011). Every time, they always seem to be on opposite sides of a snark-off, and their chemistry seems to be at its best when they're sniping at each other.
- Wild Hair: The Who producers seemed to notice this, as they seemed to make his hair more spiky and vertical anytime the Doctor got excessively hyper or unhinged (see "The Waters of Mars" or The End of Time). He almost had "Mood Hair".