Marvin: "I am at a rough estimate thirty billion times more intelligent than you. Let me give you an example. Think of a number, any number."
Zem: "Er, five."
Marvin: "Wrong. You see?"

"My capacity for happiness," he added, "you could fit into a matchbox without taking out the matches first"

"What's up?" [asked Ford.]
"I don't know," said Marvin, "I've never been there."

"I've seen it. It's rubbish." About a Magrathean sunset that Arthur finds magnificent.

On being left in a parking lot for 500 million years: "The first ten million years were the worst. And the second ten million years, they were the worst too. The third ten million years I didn't enjoy at all. After that I went into sort of a decline"

Zaphod: "Can it Trillian, I'm trying to die with dignity."
Marvin: "I'm just trying to die."

"Simple. I got very bored and depressed, so I went and plugged myself in to its external computer feed. I talked to the computer at great length and explained my view of the Universe to it," said Marvin.
"And what happened?" pressed Ford.
"It committed suicide," said Marvin and stalked off back to the Heart of Gold.

Marvin: "And then of course I've got this terrible pain in all the diodes down my left side."
Arthur: "Is that so?"
Marvin: "Oh yes. I mean I've asked for them to be replaced, but no one ever listens."
Arthur: "I can imagine"

Trillian: "that's just fine, really... just part of life."
Marvin: "Life. Don't talk to me about life."

"I think you ought to know I'm feeling very depressed."

"Was I amongst friends when the Haggunenon admiral evolved into a life pod and everybody aboard his flagship escaped leaving me aboard as it steered itself into the nearest star?
Was I amongst friends when I was left to walk in circles on a swamp planet?
Left to park cars outside a restaurant for millenia?
Left for the Krikkit robots to use for batting practice?
Friend? I don't think I ever came across one of those, sorry, can't help you there."