I, being a huge fanboy geekatron monster from the future, have my own opinions on the subject.
I will cast all the Doctors and in some cases the companions.(do to the nature of Doctor Who, with it's missing episoded, I am not familiar with all the companions) I will try to be faithful to the time period that the originals were cast in, and I will try to avoid the Hyperbole of superstar casting.
This is a work in progress. I hope to be done by Christmas
I am totally taking liberties with historical facts concerning the show. remember we are in an alternate time line
I will now cast the first episode, An Unearthly Child.
The Doctor (1963-1966)
David Wayne has always been a sensitive caring hardass. His temperament is perfect to play the stern scientist and the loving grandfather.
Susan, the Doctor's Granddaughter
yes, you know her from Lost In Space, but before that she was on the Danny Thomas Show. She is a talented kid actor with a precocious streak.
Sexy and smart as bat-girl..Ms. Craig would be the perfect school teacher and quasi romantic lead in this series.
Who else could keep up with this crew. Bixby would be the perfect smart and savvy teacher and aren't he an Yvonne Craig the perfect sci-fi couple.
The Doctor (1966-1969)
the second Doctor was a man of action, that action was mostly running away. There was a certain comic brilliance to the genius that would rather talk than fight. The musical master of talking his way into and out of anything was the amazing Danny Kaye.
so...in a world where Doctor Who is American, Star Trek must be British. Instead of donning Federation Red, the young exuberant actor dons a kilt to play the Doctor's faithful Highland companion. Secretly a master of accents and brilliant character acting. Walter Koenig would be totally in his element.
As we move on to the third Doctor, we hit territory that is more familiar to American Audiences. This is, for most of us, the earliest Doctor we can recall seeing full episodes of on the PBS. I have spent much time considering the American Casting. There are lots of companions in this one.
The Doctor (1970-1974)
Aristocratic and stodgy and a product of good breeding. Hillerman is the perfect choice for a less Timey Wimey Doctor. He can also Masquerade as country Doctor John Smith.
although quite attractive, the point of Liz Shaw was to give the Doctor a companion that could keep up Science wise. Liz Shaw was smart and a little cold.
Sally Kellerman could play this role perfectly.
Brigadier Alistair Gordon Lethbridge-Stewart
Tough as nails and smart as a whip. The perfect Brig to deal with Hillerman's proper Doctor.
Captain Mike Yates
The Mod Squad's Pete has the scruffy look and proper attitude to play the mistakenly disgraced but always loyal Captain Mike Yates.
Sergeant John Benton
this is a weird one because nobody remembers Robert Brown. Starring as the Eldest of the Bolt Brothers on "Here Come the Brides", Brown could play the sensitive soldier who is loyal and honest and brave. He's the edgy boy scout with a wise streak and he's a bit of a wise-ass.
After the departure of Liz Shaw the producers wanted an assistant that was less smart and more accessible to viewers. Goldie Hawn was the best woman for the job. She was young and hip and got into lots of troubling situations when the Doctor was not listening.
The women's movement ended her tenure as companion. the character, perceived as dumb, was replaced instead of changed to fit a new criteria.
Sarah Jane Smith
Liz Shaw was seen as too brainy and Jo Grant was seen as flighty..enter the perfect companion. Sarah Jane was perfect. Smart, intrepid and independent, Sarah Jane was the best of all worlds. She was the fan favorite for decades.
Who better than Diane Keaton to play this role.
Crazy, frantic, and a little intense, Bruce Dern was wonderful in becoming the Doctor's greatest Nemesis. Repeating the part many times during the 3rd Doctor's run. He was evil incarnate with a blackened heart and a brain filled with warped genius.
The Doctor (1974-1981)
Dr. Harry Sullivan
Only a companion for a short while Dr. Harry Sullivan was UNIT's Medic. Kent McCord more than fit as the Doubting Thomas thrown into a world of adventure that he totally can't comprehend
Maren Jensen took over the companion position after Sarah and Harry had left. A primitive from a savage planet, she had no problem fighting and even killing her enemies. The Doctor often takes issues with her more drastic behaviors.
Tony Jay is a talented voice over artist. He has starred in the original Beauty and the Beast Television series and the Mighty Max cartoon. He has the perfect superior tone to play the Doctor's faithful dog.
the most hated companion ever. Scott Baio signs on as the other dimensional mathematical genius who gets killed trying to take down a cyberman with a merit badge
Deborah Van Valkenburghfres from her role in Warriors, the actress brings her tough interpretation to the part of misplace flight attendant Tegan Jovanka
Her family killed by the reborn Master.\
Jami Gerts add passion and spark to the role of the Astrophysics prodigy
largely ignored after the John Hillerman days. The Master is again revived in the form of the Great Christopher Lloyd
The Doctor (1981-1984)
The eclectic performance sent the Doctor back to a world of 1930's cool and class, a definitive Jazz Age Doctor
turns is a stellar performance as a 1950's public school thug charged with the task of betraying the Doctor
The Doctor (1984-1986)
truth be told, John Larroquette could have been the greatest Doctor ever, but the producers dressed him in a bright multi-colored costume and made him slightly homicidal. Larroquette wanted to play the role more mysteriously, but the producers gave him no control
Mel's job is to push and prod the Doctor to take care of himself. She is perky, and bright, and shiny. Marisa Tomei took on a similar character in the first season of "A Different World"
The secret future amalgamated Doctor Identity is a small but commanding role. Jimmy Smitd would fill those shoes nicely. He is a brilliant television litigator who can totally put the Doctoe on trial
The Doctor (1987-1989)
Scolari was given the task of making the Doctor likable again. He was dark and mysterious and yet he juggles, rides a unicycle, and mismatches his cliche's. His fun and sometimes runs away. It is a return to the days when Danny Kaye played the Doctor.
1996 BBC Film
in an attempt to revive the series the BBC chose a non-American to take the role and Jude Law was cast in the story of an all too romantic Doctor Who
To our surprise Peter Scolari makes a cameo for the regeneration scene
Minnie Driver was cast as the first ever companion with a romantic slant. It was inevitable, but the world was not ready for a British Doctor with British sensibilities
the best thing about the Doctor Who Revival of the Nineties.
Doctor Who 2005
To spark interest in the new series, the producers cast
sci fi/fantasy fan favorite David Boreanaz as the Doctor. Boreananz was made for the brooding danger junkie living in self exile
Fresh off her role as the Born Again Bitch in the cult classic "Saved" and her singing career far behind her, Mandy Moore added an odd freshness to the role of companion. She added depth and a sense of self-sufficiency to a role that had previously been an excuse for the Doctor to rescue someone.
Another nod to the huge number of fans in the United Kingdom. British Actor Benedict Cumberbatch was chosen to play the futuristic time agent who has a polymorphic sexuality and a criminal streak. He would later be spun of into the more adult series Torchwood.
Doctor Who 2005-2010
much more likable than his predecessor, Noah Wylie was more concerned about redemption than guilt for his Doctor.
Billed as a much more romantic Doctor, female fans flocked to the series causing a ratings upsurge and international acclaim.
Casting former child actor Dule Hill was unexpected, but the jealous ravings and over all insecurities of Rose's ex-boyfriend were handle wonderfully by this man who has taken his whole life to perfect his craft.
Contract issues made this difficult. Tina Fey was able to do a Christmas special but then had issues with her bosses at SNL. She finally returned to be a regular companion after her contract had expired.
After an extensive search, producers decided upon supporting actress Meagan Good to assume the tough persona of Martha Jones, medical student and Doctor Who rebound girl.
Doctor Who (2010-2013)
When it comes to the king of quirk, the spinning of serious to childish on the turn of a dime. Zachary Levi is totally the man.
Quippy. strong willed and super model legs, The part of Amy Pond was made for Dianna Argon. The girl who waited needs to wait impatiently and with attitude.
Acting since he was a boy opposite the likes of Hugh Grant. Nicholas Hoult can play the impossibly loyal and steadfast Centurion of Amy's heart. They are the romantic couple of the sci-fi ages, more tragic than the Doctor and Rose.
The part of River Song the, The Doctor's out of sync time traveling criminal wife, should be wacky and a bit psychotic. This will be one wild a wacky ride.
Clara Oswald (the impossible girl)
Just wrapping on Parenthood and starring in the new film "The Duff". Mae Whitman has been spunky, Bossy, Plucky, and Independent. She is the perfect choice to play the Impossible girl.
THE WAR DOCTOR
Doctor Who 2014-
He's been Jesus, He's been a heartless self-serving Lawyer and he's been a super spy. Victor Garber is totally the failed minimalist and ersatz magician that is the Doctor,
J. August Richard
He's been a soldier sidekick to a vampire, he's been a dedicated father turned into a war machine. He's been the fighter with regrets.. A damn fine choice to play the soldier turned maths teacher, and Clara's new boyfriend.
She's been cold and sexy on Cheers, She's been wacky and macabre in the Broadway Version of the Addams Family.
Can anyone else pull off the newest Incarnation of the Doctor's Nemesis. I don't think so