(All quotes here are from the book series.)
"I think you ought to know I'm feeling very depressed."
"I'm not getting you down at all, am I? I wouldn't like to think I was getting you down."
"Here I am, brain the size of a planet and they ask me to take you down to the bridge. Call that job satisfaction? 'Cos I don't."
"'Let's build robots with Genuine People Personalities', they said. So they tried it out with me. I'm a personality prototype. You can tell, can't you?"
"Sorry, did I say something wrong? Pardon me for breathing, which I never do anyway so I don't know why I bother to say it."
"Funny how just when you think life can't possibly get worse it suddenly does."
"Do you want me to sit in a corner and rust, or just fall apart where I'm standing?"
"You think you've got problems. What are you supposed to do if you are a manically depressed robot? No, don't bother to answer that, I'm fifty thousand times more intelligent than you and even I don't know the answer. It gives me a headache just trying to think down to your level."
"Life. Loathe it or ignore it, you can't like it."
"It's part of the shape of the Universe. I only have to talk to somebody and they begin to hate me. Even robots hate me. If you ignore me I expect I shall probably go away."
"But I'm quite used to being humiliated. I can even go and stick my head in a bucket of water if you like. Would you like me to go and stick my head in a bucket of water? I've got one ready. Wait a minute."
"The first ten million years were the worst, and the second ten million years, they were the worst too. The third ten million I didn't enjoy at all. After that I went into a bit of a decline."
"You don't like talking to me do you?"
"Making it up? Why should I want to make anything up? Life's bad enough as it is without wanting to invent any more of it."
"My capacity for mental activity of all kinds is as boundless as the infinite reaches of space itself. Except of course for my capacity for happiness. My capacity for happiness you could fit into a matchbox without taking the matches out first."
"Why stop now just when I'm hating it?"
"That young girl [Trillian] is one of the least benightedly unintelligent organic life forms it has been my profound lack of pleasure not to be able to avoid meeting."
"Friend! You'll have to excuse me while I try and remember what the word means. My memory banks are not what they were, you know, and any word which falls into disuse for a few zillion years has to get shifted down into auxiliary memory backup."
"Is there any last service you would like me to perform for you perhaps? A piece of paper that perhaps you would like me to pick up for you? Or maybe you would like me to open a door? Don't seem to be any doors around at present, but I'm sure that if we waited long enough, someone would build one. And then I could open it for you."
"Ha! What do you know of always? You say 'always' to me, who, because of the silly little errands you organic life forms keep on sending me through time on, am now thirty-seven times older than the Universe itself? Pick your words with a little more care and tact."
Marvin's PoemNow the world has gone to bed,
Darkness won't engulf my head,
I can see by infrared,
How I hate the night.
Now I lay me down to sleep,
Try to count electric sheep,
Sweet dream wishes you can keep,
How I hate the night.