As a Facebook status update after viewing "The Waters Of Mars", I asked if there was anything more heartbreaking during the Tennant years than the Doctor telling someone that he was sorry; that he was so very sorry.
Here are a list of examples during the four seasons of Tennant's tenure, but without the last five specials ("The Next Doctor", "Planet Of The Dead", "Waters Of Mars", and "The End Of Time (Parts One & Two)".........
The Doctor and Cassandra/Rose go down metal steps into Intensive Care. They find themselves in the huge cavernous chamber, looking upon row and row of green doors. The Doctor walks along one of the rows and opens a door with his sonic screwdriver. A man, covered in boils and surrounded by smoke looks back at them.
That's disgusting. What's wrong with him?
THE DOCTOR (to the man, horrified)
I'm sorry. I'm so sorry.
Cassandra/Rose holds her nose whilst the Doctor closes the door gently.
The children cheer even harder and start chanting 'Kenny! Kenny! Kenny!', patting him on the back. Only the Doctor and Sarah Jane stand separate from the merriment. Sarah Jane looks distraught.
SARAH JANE (quickly)
It's all right. He was just a... daft metal dog. Fine, really.
And she bursts into tears. The Doctor puts his arm around her comfortingly.
"AGE OF STEEL"
Why am I cold?
Oh, my God. It's alive. It can FEEL.
We broke the inhibitor.
(leans over the Cyberman, touches its head. Sincerely--)I'm sorry. I'm so sorry.
The Cybermen, all over the factory, fall around and start twitching, crying out and clutching their metal skulls. One of them has caught sight of their reflection in a piece of metal and is whimpering and touching its face and fingering its reflection.
"LOVE AND MONSTERS"
I stopped it, but... I wasn't in time to save her.
(he looks Elton in the eyes)
"ARMY OF GHOSTS"
Like a psychic link. Course you want your old dad to be alive, but you're wishing him into existence. The ghosts are using that to pull themselves in.
You're spoiling it.
I'm sorry, Jackie, but there's no smell, there's no cigarettes. Just a memory.
I've gotta go, I'm sorry.
He puts the phone down
Lance swings the axe -- the Empress swings around and hisses at the last moment -- then he stops. He glances round at Donna and starts to laugh and the Empress laughs with him.
LANCE(to the Empress)
That was a good one. Your face!
Lance is funny.
Sorry for what? Lance, don't be so stupid! Get her!
LANCE (staring at her pityingly)
God, she's thick.
"SMITH AND JONES"
I had a cousin. Adeola. She worked at Canary Wharf. She never came home.
I was there. In the battle.
Normally, I'd offer you a lift home, but somebody nicked my motor. So I need you to take a message to Sally Sparrow. And I'm sorry, Billy, I am very, very sorry. It's gonna take you a while.
That's why they cover their eyes. They're not weeping, they can't risk looking at each other. Their greatest asset is their greatest curse. They can never be seen. The loneliest creatures in the universe. And I'm sorry, I am very, very sorry, it's up to you now.
"LAST OF THE TIME LORDS"
No! (fires laser at the DOCTOR but the field deflects it)
I'm sorry. I'm so sorry.
Then I'll kill them!
(aims laser at MARTHA and her family but the DOCTOR throws it across the room telekinetically. Unarmed, the MASTER panics)
You can't do this! You can't do—It's not fair!
"VOYAGE OF THE DAMNED"
(hysterical, to THE DOCTOR)
Bring him back! Can't you bring him back? Bring him back, Doctor!
I'm sorry, I can't.
You promised me!
I know. I'm sorry. I'm sorry.
"THE POISONED SKY"
Right, Donna, listen, on the back of his neck on his collar there's a sort of plug, like a hole. The Probic Vent. One blow to the Probic Vent knocks 'em out.
But he's gonna kill me.
I'm sorry. I swear I'm so sorry. But you've got to try.
She picks up the mallet that the Doctor uses so happily when piloting the TARDIS. She sneaks behind the Sontaran and hits his probic went, knocking him out.
"SILENCE IN THE LIBRARY"
In her home, the Girl is on the ground crying in agony. Under her, there's a symbol on the floor identical to the one on the lens cover of the security camera.
No, stop it, no, no!*** The Girl's words appear on a display of the camera.
Ooh, I'm sorry. I really am, I'm sorry, I'm so sorry.
(he puts down the sphere) It's alive.
You said it was a security camera.
It is. It's an alive one.
Actually, Proper Dave, could you stay where you are for a moment?
I'm sorry. I am so, so sorry. But you've got two shadows.
Everybody looks at Proper Dave's shadows in horror.
It's how they hunt, they latch on to a food source and keep it fresh.
The Doctor wasn't the only one to employ that phrase, but there was really only one other time when it cut close to his hearts.....
"FOREST OF THE DEAD"
Here's a little something from the Missus....
Doctor... one day I'm going to be someone that you trust completely, but I can't wait for you to find that out. So I'm going to prove it to you. And I'm sorry. I'm really very sorry.
She whispers something in his ear, something that stuns him completely.
"THE STOLEN EARTH"
But... if the Earth's been moved... they've lost the sun.
(urgently, to the Doctor who is immersed in the computer)
What about my Mum? And Grandad? They're dead? Aren't they? Are they dead?
I don't know, Donna. I just don't know. I'm sorry. I don't know.
"THE JOURNEY HOME"
I'm sorry, there's nothing else we can do.
No, I know.
The Supreme Dalek sends a death-ray Jack's way and he screams in pain and falls to the floor, apparently dead.
ROSE(falling to her knees beside him in distress)
Jack! Oh, my God. Oh, no...
THE DOCTOR(kneels beside her)
Rose...(softly, so only she can hear)
Come here. Leave him.
They killed him.
I know. I'm sorry.
That's all I have for now. I'm sorry. I'm so very sorry.....