Jon Pertwee played the Third Doctor for 5 seasons from 1970 – 1974. He passed away in 1996.
Exile to Earth by the time lords for interfering with time. So he joins up with UNIT and works as their Scientific Advisor
He has had the knowledge of time travel removed from his mind and his TARDIS is disabled
This is when we really first start to learn about Gallifrey and the other Time Lords
The Doctor was retconned from a human to a Time Lord
Since they were reworking the show to keep it on Earth for budgetary reasons they also reworked their focus to help earn more teen and adult viewers and no longer consider it a children’s show.
More action, more adventure, it was in color, and more horror and violence.
Caroline John played Liz Shaw for The Third Doctor’s first season. She was his assistant at UNIT and an accomplished scientist.
Katy Manning played Jo Grant for the next three seasons and she was also his assistant at UNIT (we’ll see her introduced at the start of Terror of the Autons) She’s as close to Rose as Classic Who companions get.
Elisabeth Sladen came in for the last season of the Third Doctor as Sarah Jane Smith, but far from his assistant, she was a journalist who discovered that UNIT existed and wanted to know what they were up to.
And very fitting, since the Third Doctor spent so much time without his TARDIS, he got his own antique roadster which is bright yellow and named Bessie. Much like the TARDIS, Bessie is almost a companion.
UNIT is run by Brigadier Lethbridge-Stewart and his second-in-command is Captain Mike Yates
Who is The Doctor
If you keep in mind that this era of the Doctor was inspired by James Bond you will quickly understand The Doctor. Jon Pertwee and James Bond writer Ian Flemming worked together in World War II in the British Naval Intelligence Division reporting directly to Prime Minister Winston Churchill. He played The Doctor as a refined gentleman, complete with velvet sport coats, capes and frilly shirts.
One excellent word to describe him is dashing, dapper is another good one if you’re looking for two words. He was sure of himself and not afraid to give orders. He worked on inventions, he was an expert linguist and a martial arts expert. While it doesn’t come out in the show, I would expect that the Third Doctor had a knowledge of fine wines, started his own craft brewery long before it was popular, could recite all 154 sonnets of Shakespeare and wore a tuxedo every night after 6pm just because he made it look so good.
In short, he was the original most interesting man in the world. Just watch his coiffed hair, I can’t think of a single instance where it gets messy or out of sorts.
With the Third Doctor we learn a lot about the Time Lords like their biology, that the planet is name Gallifrey, that they have rules and a hierarchy and that they love to bend and break the rules all the time as they see fit.
We learn a lot about UNIT and why it was formed
Played by Roger Delgado from 71 to 73
In Terror of the Autons we see the Master as he was originally conceived. You could say he is pure evil. Willing to kill whoever stands in his way all in the name of the sport of outwitting the Doctor. He is a renegade Time Lord with his own TARDIS (a newer TARDIS than the Doctors) and is very adept at mind control. He appears in every story of that season and then sporadically for the rest of Doctor Who.
Roger Delgado was the first major Doctor Who actor to die when he was killed in a car accident while filming on location in Turkey for a movie that was unrelated to Doctor Who.
So many stories we could have watched that connect to the episodes we are watching right now like the first appearance of the Sontarans in The Time Warrior or seeing the first Silurians in The Silurians and The Sea Devils, or seeing the first Autons and the Nestene Consciousness in Spearhead from Space. As it stands we will see the Autons because I couldn’t resist picking the first appearance of The Master.