You know how it is; you put things off for a day and next thing you know, it's a hundred years later.
S20 E1Arc of Infinity
It's too late! Omega controls the Matrix!
S20 E2Snakedance
Once a man fell asleep and dreamt he was a frog. When he woke up, he didn't know if he was a man who dreamt he was a frog or a frog who was now dreaming he was a man.
[Nyssa and Tegan are sitting outside the Snake Mouth cave when a puppeteer runs up to them]
PPuppeteer
Excuse me.
[His tray is full of jointed wooden snakes on sticks]
Oh, no thank you. No, really, not at the moment.
PPuppeteer
Look. [begins to show them off]
Yes, it's very good.
[The puppeteer waves one in front of Tegan, who screams and runs away]
Tegan! Tegan! [goes after her]
[Adults and children alike are watching a Punch and Judy show]
PPunch
That's the way to do it! [hits Judy]
JJudy
He struck me! [fetches a large saucepan]
PPunch
I don't care!
JJudy
Don't care. Was made to care!
[And the Judy puppet fetches Punch a clout on the head. Punch fetches his large club and battle is joined until Judy is dead]
PPunch
Wake up, Judy!
CCrowd
Aw.
[Ambril and Lon enter]
PPunch
Oh dear. Oh dear, oh dear.
S20 E3Mawdryn Undead
Well, there's a probability of anything. Statistically speaking, if you gave typewriters to a treeful of monkeys, they'd eventually produce the works of William Shakespeare.
[trying to draw the Doctor's attention away from his conversation with Tegan to the approaching craft on the viewscreen] Doctor...
Of course, you and I both know that at the end of a millennium they'd still be tapping out gibberish.
And you'd be tapping it out right alongside them. I only asked you a simple question.
In the name of all that is evil, the Black Guardian orders you to destroy him now!
[Upon seeing Mawdryn's disfigured colleagues]
Who are they?
Fools, who tried to turn themselves into Time Lords.
S20 E4Terminus
If we don't do something quickly, the whole universe is going to be destroyed!
The outside universe is breaking through!
(to Turlough) This is your last chance, boy... I will not say this again... KILL THE DOCTOR!
S20 E5Enlightenment
But what if the White Guardian tells me something important?
...Thank him politely. [The Doctor smiles] Won't be long.
SStriker
You are not an Ephemeral. You are a... a time dweller. You travel in time.
You're reading my thoughts.
SStriker
You are a Time Lord, a lord of time. Are there lords in such a small domain?
And where do you function?
SStriker
Eternity. The endless wastes of eternity.
[Turlough attempts to communicate with the Black Guardian]
You must answer. I need your help! What's going on here?
[The Black Guardian appears and suddenly starts throttling Turlough]
You are pathetic! I have watched your progress. You have had many opportunities to destroy the Doctor.
[gasping for breath] I cannot kill him!
Then I condemn you to everlasting life. You will never leave this ship! [throws Turlough to the deck, then disappears]
S20 E7The Five Doctors
TDThird Doctor
I've reversed the polarity of the neutron flow so the TARDIS should be free of the force field now.
These quotes come from Wikiquote's Doctor Who pages and are available under the Creative Commons Attribution-ShareAlike License.