How about the Japanese Howard Cosell from Better Off Dead?
:smack: You are correct, of course. Never mind.
I love the scene in Shawshank Redemption in which Andy plays a duet from The Marriage of Figaro over the prison’s public address system, and all the prisoners stand in awe.
People of Earth, your attention please, this is Prostetnic Vogon Jeltz of the Galactic Hyperspace Planning Council. As you will no doubt be aware the plans for the outlying regions of the galaxy require the building of a hyperspacial express route through your star system. And, regrettably, your planet is one of those scheduled for demolition. The process will take slightly less than two of your Earth minutes. Thank you very much.
Would you like to know more?
Hey YOU! On the water skis!
Attention. Here’s an update on tonight’s dinner. It was veal. I repeat, veal. The winner of tonight’s mystery meat contest is Jeffrey Corbin who guessed “some kind of beef”.
“GOOOOOOOOOOOOOOOOOOOd Morning Vietnam!”
It’s been a while since I’ve seen it, but I’m reasonably sure that the show is on the PA as well as being broadcast…
Along the same lines you have SHODAN and Xerxes from System Shock 1&2, and GLaDOS from Portal.
“I have complete control over this entire level. With cameras as my eyes and nodes as my hands, I rule here, insect.”
“The Enrichment Center is committed to the well being of all participants. Cake and grief counseling will be available at the conclusion of the test. Thank you for helping us help you help us all.”
Damn! That was my favorite! 
From Real Genius, Mitch is on the speaker.
MITCH
(disguising his voice, into a microphone)
Kent. Kent. Wake up, Kent.
INT. KENT’S ROOM-SAME TIME
Kent begins to stir. We can HEAR Mitch’s voice coming from Kent’s head. At first he thinks he’s dreaming.
MITCH (V.O.)
I’m talking to you, Kent.
KENT
What?
MITCH (V.O.)
I said I’m talking to you.
KENT
(shaking his head, violently)
No!
MITCH (V.O.)
Yes.
KENT
(slapping himself)
I’m not asleep. I must be overworked.
MITCH (V.O.)
You’re not overworked, Kent.
KENT
Well, I’m not insane!
Silence.
KENT (CONT’D)
Am I?
INT. CHRIS AND MITCH’S ROOM
MITCH
That remains to be seen, Kent. But we are having a conversation.
INT. KENT’S ROOM
KENT
I have to metabolize this. Um… who is this?
MITCH (V.O.)
This is Jesus, Kent, and you’ve been a very naughty boy.
KENT
(cracking up, laughing)
All right! Who is this?! Bodie? Carter?
MITCH (V.O.)
I am known by many names. I am the One. Turn to me and be saved.
KENT
Oh, Sure.
MITCH (V.O.)
Cut the crap, Kent, you’ve built a weapon.
KENT
How did you know that?
MITCH (V.O.)
I know everything.
KENT
Oh. God.
INT. CHRIS AND MITCH’S ROOM
MITCH
That’s right, Kent. Where is the laser now?
INT. KENT’S ROOM
KENT
I can’t tell you.
MITCH (V.O.)
How would you like to burn for the rest of time?
KENT
(panicking)
No, they’re testing it on the twenty-seventh but I don’t know where. It’s classified.
MITCH (V.O.)
Oh.
KENT
What?
MITCH (V.O.)
Nothing. I want you to think about what you’ve done and repent, and from now on, stop playing with yourself.
KENT
It IS God!
Not exactly a quote, but near the end of “A Fistful of Yen” in “Kentucky Fried Movie”, the alarm that sounds like a man saying “honk honk” on a bullhorn actually is that.