Star Trek: Deep Space Nine Season 4 Episode 11

Odo: I've found that when it comes to doing what's best for you, you humanoids have the distressing habit of doing the exact opposite.

Joseph: But what you're asking me to do is wrong. You can't go around making people prove they are who they say they are. That's no way to live and I'm not gonna go along with it.

Sisko: Sir, the thought of filling the streets with armed troops is as disturbing to me as it is to you, but not as disturbing as the thought of a Jem'Hadar army landing on Earth without opposition. The Jem'Hadar are the most brutal and efficient soldiers I've ever encountered. They don't care about the conventions of war, or protecting civilians. They won't limit themselves to military targets. They will be waging the kind of war Earth hasn't seen since the founding of the Federation.

Joseph: Benjamin Lafayette Sisko! What the hell's gotten into your head? You actually thought I was one of them, didn't you?
Sisko: I don't know. I wasn't sure.
Joseph: This business has gotten you so twisted around that you can't think straight. You're beginning to see shapeshifters everywhere. Maybe you ought to think about something for a minute. If I was a smart shapeshifter, a really good one, the first thing I'd do would be to grab some poor soul off the street, absorb every ounce of his blood, and let it out on cue whenever someone like you tried to test me. Don't you see? There isn't a test that's been created that a smart man can't find his way around. You aren't going to catch shapeshifters using some gadget.

Jaresh-Inyo: Earth is in your hands, gentlemen. Do what needs to be done.
Leyton: Thank you, sir. You've made the right decision.
Jaresh-Inyo: I hope you're right... for all our sakes.

(after Odo morphed back from being a seagull)
Benteen: Well, if you ask me, that was a pretty convincing seagull.
Odo: Thank you, but I don't know if the other gulls would agree.

Jaresh-Inyo: It took Earth centuries to evolve into the peaceful haven it is today. I would hate to be remembered as the Federation President who destroyed paradise.

(talking about gods)
Worf: Our gods are dead. Klingon warriors slew them all millennia ago. They were more trouble than they were worth.
Kira: I don't think I'll ever understand Klingons.
O'Brien: Don't worry about it, Major. Nobody does. That's the way they like it.

Quark: I know exactly what you mean. When the Great Monetary Collapse hit Ferenginar, I was hundreds of light years away, working as a ship's cook on a long-haul freighter. I can't tell you the heartbreak I suffered, knowing that rampant inflation and currency devaluation were burning like wildfires through the lush financial foliage of my home. It still depresses me even today.