By now you’ve probably seen the Buzzfeed post created by Jamie “Friendly Old Bum” Hooper titled What If “Doctor Who” Was American?. He has even done an amazing job of creating portraits for each of his would-be Doctors. If you haven’t seen it, you should have a look before you continue reading.
Personally, I think that Jamie has too much faith in American TV, especially old pre-HBO American TV.
If Doctor Who had been created by an American network in 1963 the Doctor probably would have been played by (in chronological order):
1 – John Wayne
2 – Lee Marvin
3 – William Shatner
4 – Clint Eastwood
5 – Chuck Norris
6 – Charles Bronson
7 – Bruce Willis
8 – Sylvester Stalone
9 – Dwayne Johnson
10 – Nicholas Cage
11 – Vin Diesel
12 – Stephen Amell
There would have been no “War Doctor” because when the time war happened, the Doctor would have single handedly killed all 800 billion Daleks armed with just a shotgun and a bowie knife.
Also the sonic screwdriver would be a revolver. The Tardis would be red and shaped more like a racing car with laser cannons, all of the companions would have been female and would have slept with the doctor and most episodes would have ended when the Doctor blew the bad guys up.
Americans created Star Trek just a few years after the birth of Who, but Star Trek was unusually optimistic for US TV, it still had a good deal of sex and violence and it lasted only 3 years initially (until its revival in the 1980s.) Even the latest Star Trek films are primarily about things blowing up and and most of the stars are very young and very pretty.
It is, in large part, the British sensibility and British tastes that make Doctor Who popular (even in the US) and that keep it going after 50 years. As a US series it would have been short lived and forgettable.