Castle: Paul is the writer, Lone Vengence is the subject. That's their relationship. It's you and me all over again, but I'm Paul and you're Lone Vengence.
Beckett: Really, Castle? Is that how you see me? Like a sword-wielding killer?
Castle: Depends. Will you be scantily clad?
Beckett: In your dreams.

Castle: Quick, who do you want to play you in the Nikki Heat movie?
Lanie: [As if it's the most obvious answer in the world] Halle Berry.
Castle: See? Some people are just great at that game! You know who we could get for you? Angelina? No. Kate Beckett�� Kate Beckinsale. We'll call you K-Becks!

Castle: She grew up so fast.
Martha: Well, what do you expect? Her to live here forever?
Castle: Well, her, yes. You...
Martha: Watch it.

Castle: She may have built up a wall between us, but I am going to build a door in that wall. Or put up a ladder. [thinking] Or dig a hole.

Castle: So, I wear boxers. What do you wear? Thong? Cheekies? I told you mine! Bloomers? Granny panties? [Eyes opening wide] Commando?

Castle: Tell me you've arrested Gates
Beckett: Not even close. I mean, I don't know how, Castle, but he killed Kim Foster and he's gonna do it again.
Castle: There's been no developments? Usually you call me with news. [He stops in realization, his eyes grow wide. Beckett cringes, knowing she's been caught] You called to seek my council!
Beckett: [Very slightly sheepish] I wouldn't say it exactly like that...
Castle: No, no, no! You're hoping I had some wild theory. Some sort of penetrating insight that would lead us to a breakthrough.
Beckett: Well... do you?
Castle: [Stops, as if trying very hard to come up with something. Exhales exasperatedly] Gah! I got nothing.

Castle: Thank you.
Beckett: Always.
Season 4

Castle: The last time I saw you in your PJs after eight am, I think you were four.
Alexis: We're off today. Teacher's retreat. I didn't feel like getting dressed.
Castle: This wouldn't have anything to do with Ashley, would it?
Alexis: Did I do the right thing, breaking up with him?
Castle: Oh, sweetie, I don't know. That's something only you can answer.
Alexis: It sucks. I miss him a lot.
Castle: Yeah, well you're not doing yourself any favours sitting around reading Pride and Prejudice. That's just gonna make it worse. Might as well be listening to Adele.
Alexis: Hey, she totally gets it. And so does Jane Austen.

Castle: Then we can take over the world! [Laughs evilly]
Alexis: Not helpful.
Castle: But evil!

Castle: There are two things in abundance in South Africa: racial hatred and diamonds.

Castle: This is both literally, and figuratively, cool.

Castle: This place looks like my first apartment. We used to have cockroach races. I wonder if that's how Kafka got the idea?

Castle: Three men huddled around a computer... that better not be porn. And if it is, I want in.

Castle: Well, apparently, in an actual homicide, they don't know who did it until the guy gets caught.

Castle: Well, the pen is mightier than the sword, but a baseball bat can be pretty effective too.