(Photo: BBC America) 
For a TV show that is so devoted to travelling, Doctor Who has a curiously homespun, self-contained feel to it at times. So much so, that when an actor of international acclaim and stature finds their way into the Doctor’s orbit, it can blow minds.
It’s one thing to capture actors just as their careers take off, as Doctor Who was lucky enough to do with Andrew Garfield, Carey Mulligan, Sophie Okonedo and even (arguably) James Corden, or to be responsible for the breakthrough roles of actors such as David Tennant, Karen Gillan, Matt Smith or Jenna Coleman. It is quite another to bring in someone whose acclaim is arguably on a par with that of the Doctor themself. 
So, with the announcement that Neil Patrick Harris is signed up to play "the greatest enemy the Doctor has ever faced" in the forthcoming 60th anniversary special, here’s a quick reminder of some of the greatest moments of stunt casting in Who history:
1. Alan Cumming

It’s hard to be clear exactly who should be the more flattered: Alan Cumming to have been invited to take part in Doctor Who, or Doctor Who to have secured the services of Alan Cumming. This is an actor whose louche presence has blessed the stage in the West End and Broadway, many international hit TV shows, including The Good Wife, Bond films and, oh yes, he’s an X-Man. And he’s an acclaimed actor who has built up a phenomenal cult of personality around what is, after all, a phenomenal personality. His performance of King James, played with softness overlaying a core of steel, catches the entitlement, daftness and pomposity of English aristocracy in a way that thrillingly familiar to viewers all over the world.
2. Kylie Minogue

It’s hard to understate the excitement that was generated by the casting of Kylie Minogue as Astrid Peth in “Voyage of the Damned.” From a British perspective it was as if Madonna had agreed to appear on a Dalek spaceship. British audiences had grown-up watching Kylie in the Australian soap Neighbours, and then supported her stellar career as a pop singer grow and mature from the late 1980s on to today. Despite her Antipodean origins, she is considered to be a British national treasure and this fact alone could easily have overshadowed the reality that she was inhabiting. Thankfully she is a great actress, and so that was never an issue.
3. John Hurt

You hear the voice first: “What I did, I did without choice.” For many other actors that might not have been enough, but John Hurt’s unique tones, appearing from somewhere in the Doctor’s time-stream, at the end of “The Name of the Doctor,” is so immediately familiar that hearts began to quicken from the second he spoke. In many ways it’s a surprise that he hasn’t been on Doctor Who before. John Hurt’s tenure as a legendary British actor of stage, screen and TV, was largely cemented during the 1970s, an era when Doctor Who was at a populist peak. But the olden days’ loss is modern times’ gain, as we get to experience him as a throwback, an untold story. The existence of the War Doctor acts as a perfect bridge between the classic and modern eras of Doctor Who, and to do that, you need some serious gravitas.
4. John Cleese

It’s a giddy cameo in lots of ways. John Cleese, star of Monty Python’s Flying Circus and Fawlty Towers, and Eleanor Bron, make a great deal out of appreciating the TARDIS as a work of art when it dematerializes from the Louvre in “City of Death.” There’s no narrative reason for them to be there. And Cleese being an icon of TV comedy at that moment, it does rather look as if Doctor Who has temporarily stopped to crowbar in a quick satirical skit, or even as if the Doctor and Romana have accidentally interrupted the real John Cleese during a contemplative moment. Nonetheless, it is real, it did happen (thanks mostly to the efforts of scriptwriter Douglas Adams) and it’s a wonderful thing.
5. Alex Kingston

Just because she is now better known as River Song, it doesn’t make Alex Kingston‘s original casting in “Silence in the Library” any less of a surprise. To British and American audiences she was the title character in The Fortunes and Misfortunes of Moll Flanders (co-starring future James Bond Daniel Craig) and had already broken hearts as Elizabeth Corday in ER. That said, Doctor Who is actually something of a return to home turf for Alex, as she made her first TV appearance on a BBC production, the children’s school drama Grange Hill.
6. Timothy Dalton

It’s not every day James actual Bond turns up, wearing the robes of a Gallifreyan leader. In fact, Timothy Dalton suddenly popping up in “The End of Time” is the only time a Bond has crossed over into Doctor Who territory, and as if to cement his status, he’s playing Rassilon. And not just any Rassilon, the statesmanlike founder of the Time Lords, no, he’s playing Rassilon as an irascible, bloodthirsty, angry warlord. Nothing like the famed noninterventionists the Doctor supposedly ran away from. In his post-Bond acting career Timothy Dalton has specialized in playing fire and brimstone baddies. He even gleefully satirized that trope, appearing as a clearly evil – but impossible to pin down - supermarket owner in Simon Pegg and Edgar Wright’s Hot Fuzz.
7. Ken Dodd

OK, this one might require a little context. To an international audience, Ken Dodd - the fellow jumping up and down in the purple uniform - may not seem to be anyone especially noteworthy, but British viewers will know him as one of the most original comedians the British Isles has ever produced. A phenomenally talented joke writer and teller with a 60 year career, Ken Dodd’s unique delivery and exceptional stamina (he would regularly perform for more than four hours at a time, even into his 80s) made him not only a familiar household presence to TV watchers, but also easy to mimic. So, even when he wasn’t on screen himself, impressionists were doing him and reminding viewing audiences of his presence. He was also a surprisingly gifted actor, in the way that a lot of comedians are, and his appearance in “Delta and the Bannermen” is not by any means solely comic. The fact that he is playing opposite Sylvester McCoy, himself a very gifted clown, merely hints at possibilities for levity that were never explored.
8. Sir Michael Gambon

It might not seem like it to an international audience but the arrival of an actual knight of the realm on the set of Doctor Who is not only rare but special. Sir Michael Gambon’s stage and film career is a remarkable thing, starting with a thorough schooling from Sir Laurence Olivier, taking in stellar performances in Dennis Potter’s The Singing Detective, and Peter Greenaway’s The Cook, the Thief, His Wife and Her Lover and coming up to date when he took over the role of Albus Dumbledore in the Harry Potter movies, after the untimely death of Richard Harris. His appearance in “A Christmas Carol,” playing a Scrooge-like character, manages to mix the casual cruelty of the very powerful with the fragility of the broken-hearted.
9. Brian Blessed

There isn’t much that Brian Blessed has not done. As well as being a very accomplished stage, screen and TV actor, he has climbed Everest; he claims to have assisted with the birth of a child (even saying that he bit the umbilical cord to sever it) and can be relied upon to turn any TV chat show upside down by sheer force of personality alone. It’s therefore quite surprising that his appearance in Doctor Who came relatively late in the classic show’s run. He’d already been the bellowing Prince Vultan in the 1980 cult movie Flash by then. He had done a turn as King Richard IV in the first season of the classic British historical sitcom Blackadder, and was a long-established star of British TV – Z-Cars, I, Claudius - right the way through the ‘60s and ‘70s when Doctor Who was establishing itself as a TV staple.
10. Sir Derek Jacobi

British character actors are known for their delight in taking on roles in which they really get to test their skills. Sir Derek Jacobi made his name taking that approach to an extreme, in iconic stage and TV roles including a great deal of Shakespeare’s leading men. His most notable TV performance was as the stuttering, weak, title role in the BBC’s acclaimed history of the Roman empire, I, Claudius. Despite the grandness of his achievements, he has never treated popular culture with disdain. This meant that when Russell T Davies was looking for an actor who could play a mild-mannered scientist at the end of time in “Utopia,” and who could then transform into the most evil Time Lord who ever lived, he knew exactly who to call.
Do you have a favorite guest star to date? Lots to choose from!