Some of my favorites from Babylon 5...
Centauri Ambassador Londo Mollari to his assistant Vir, when Vir interrupts his romantic encounter:
"What do you want now, you moon-faced assassin of joy?!?"
Commander Susan Ivanova, leading a fleet to liberate Earth, when ordered to indentify herself by an enemy destroyer blockade:
"Who am I? Iam Susan Ivanova, Commander. Daughter of Sergei and Sophie Ivanoff. I am the right hand of vengeance. I am the boot that will kick your sorry ass all the way back to Earth! I am Death incarnate, and the last living thing that you will ever see. God sent me."
Captain John Sheridan and Vorlon Ambassador Kosh Naranek, when Kosh has taken him to the abandoned, unfinished bowels of the station:
Kosh: (makes an odd sound like a dozen voices muttering, singing, crying, laughing, whispering and sighing all at once) "There"
(A door opens on groaning hydraulics)
Sheridan: "What, you want me to go inside, is that it?"
(Kosh does not answer)
Sheridan: (Peering into the darkness) "Why? What's inside there?"
Kosh: (makes the sound again) "One moment of perfect beauty."
Narn Ambassador G'Kar to Lyta Alexander, bargaining to obtain a sample of her Telepath's DNA:
"Would you prefer the mating to be conscious or unconscious? I'd prefer conscious, of course, but I don't know what your pleasure threshold is."
Minbari Ambassador Delenn, leading a squadron to defend the station against an invading force of Earth destroyers:
"You face three Minbari Warcruisers. Only one human Captain has ever defeated a Minbari warship in battle, and he is behind me. You are in front of me. If you value your lives, be somewhere else."
And of course, G'Kar reading from the holy Book of G'Quan, quoted in my sig below.