They need the man in the hood.

Diggle

Oliver: I have to warn my friends.
Sara: You said they were dead.
Oliver: They're not that easy to kill.

For the record, I hated her before we found out she was a super villain.

Felicity

Sebastian Blood: You know who he is under that hood, don't you?
Slade: I know exactly who he is. He's my friend.

Sara: Laurel's gonna kill me. She's really gonna kill me.
Oliver: She'll never know.

Who the hell is Felicity Smoak?

Quentin Lance

Oliver: Do you want Lauton arrested?
Diggle: No.

So find me a mask that conforms perfectly to my face and doesn't affect my ability to aim while I'm on the run.

Oliver

Arrow: This isn't working. I can't get close enough to Slade to hit him with the cure.
Canary: So what do we do?

Oliver: They're calling you Deathstroke.
Slade: That's a bit flamboyant. I like it.

This isn't over. I got the loose end now and no matter what happens I'm going to pull on it until your whole world unravels.

Laurel

Sara: If you had chosen differently, then it would be me haunting you at night.
Oliver: It still could be Sara. That's why we have to stop him.
Sara: What are you saying?
Oliver: He's going to use you to hurt me. Or he's going to hurt you. Stay away from me.

Arrow Quotes

Ra's al Ghul: You tasted death and you wanted more, but the truth is everyone and everything must come to an end. Even for one such as me.
Oliver: Kill me, but spare John Diggle's life. Let him go. I will beg for it.
Ra's al Ghul: You have shown tremendous strength, fortitude, power. No, Mr. Queen. I don't want to kill you. I want you to take my place. I want you to become the next Ra's al Ghul.

Laurel: Helena, you don't have to do this.
Helena: Yes, I do. Because once you let the darkness inside, it never comes out.