Well, it mostly depends on the level of imagination/visualization for each person. I, for example, see various dots, little patterns, but not much more.
Don’t worry Lord Antares. If I close my eyes, I see coloured somewhat organic shapes slowly morphing around as well and I remember having talked with some friends about this, who stated they would see those shapes too.
As for the reason: Have you noticed that when you rub your (closed) eyes, the morphing shapes intensify? Hence I suppose it has something to do with the pressure the gelatinous liquid filling the eyeball applies to the retina. Maybe it’s always wobbling against it but we only recognize when we close our eyes.
Whatever might be the reason, I think it is quite common. Nevertheless I’m interested in hearing what other members observe with closed eyes.
Take care
Auditor
I see blue, cloudy, moving shapes, which get stronger if i watch them for a while. We had a discussion about this in the family, and it turned out that we all see different colours: my brother sees red clouds, my mother green, and somebody i asked on IRC sees yellowish green.
Yes, I have, thanks for the input 
The colors start intensifying and changing.
I’m not worrying, I’m just curious 
Hey Lord Antares
I have wondered about that too. My whole life, as far back as I can remember,
when I close my eyes in the dark,
I always see big Green and Purple blobs that morph in and out of each other and move about against a dark background that has zillions upon zillions of teeny tiny points of vibrating specs of light.
Err. Now I just feel more sucky. I never see anything when I shut my eyes. XD I’ve been like that ever since I was a kid. And they’d be like “close your eyes and imagine” and I’d sit there with my eyes closed feeling like an idiot because all I saw was blackness. But yeah, I noticed now that depending on how shut my eyes are light seems to get in. Also depends what direction my ways are looking. So either complete black or “light” black? lol Yeah I dunno.
I get a field of small dots, of all different colors, and all of them are minuscule. Occasionally, I also see clouds, usually dark blue or yellow green, but this changes.
Phosphenes! 
At least, that’s the name for the ones that show up when you rub your eyes. I’ve always assumed the general always-there variety had the same name, but now that I think about it I don’t know.
I usually just get vague wavy fields, but sometimes if I rub my eyes at the right moment it all goes seriously geometric and kaleidoscopey, which is cool.
That probably is right. o.o So odd. But yeah, I see no colours. It’s kind of annoying, though, since I really had to improve my visualization just to be able to daydream. So it’s like “forced” imagination, you know? I dunno. I’m just odd and confusing. 
When I’m tired I can get surprisingly precise pictures (once considered making art out of these), but usually it’s just blobs, dots or something like an aurora.
When I am really tired, I sometimes randomly see contours of something like a cat, or a face of someone I have never met. They last for only about 1/2 second.
When I close my eyes I also see dots and things. I’ve been wandering… those things we see when we close our eyes are inspired by the light there is outside which comes through our closed eyelids, the cells perhaps which move there, the imagination plays a small role too I guess… complete darkness… hmm, want to experience that ? Go in a public toilet (those usually don’t have any windows) and close the door. You would eventually see only black…
I don’t know about the rest of you, but the darker it is, the more vivid these things are.
I just tried turning off my lights in the room to prove it.
You could also cover your whole vision with your hands.
Interesting, reminded me of the day where when I closed my eyes I would see interesting images created from webs of light. I specifically remember what looked like red light forming a spiderweb which faded from view and some multi-coloured circles and symbols came up in its place. I noticed how quickly they change too. I haven’t tried focusing on the images much lately, but I think that how well you can focus or meditate effects whether or not you see any images or how intense they are.
I dont even need my eyes closed to see these moving dots (although I cannot see them when in sunlight 
) and thats the way Ive worked for my entire life, so Ive never experienced total blackness either
I’m not sure it’s what you mean, but if you are talking about something I’ve heard called ‘the void’ I have experienced this. The moving colours are a mix of things I believe, the ones you see when first closing your eyes are usually essentially static that is caused by random firing of neurons in your eyes. Later they are basically a form of HI. I too get this. The ‘void’ experience was one that I encountered when trying WILD once. I was in an extremely relaxed state and suddenly I felt disconnected from my body, life and everything. It was as if I was floating in nothingness alone. The blackness I saw then was blacker than even when eyes are closed and covered in a dark room.
I personally found the experience extremely relaxing and would love to repeat it. I have spoken to others though who found it to be disturbing and felt incredibly lonely.
I see clouds only when I’m not drowsy. When I’m even a little bit drowsy I see clear images, which stay more and more in front of my eyes as I get closer to sleep.
This happens to me too, i see black sometimes, but there are usually shapes and moving things on my eyelids! 
I’ll take the opportunity to askthis has always bugged me a little. When you get low blood pressure and your vision fades, do you also see a bee hivelike pattern?
When I close my eyes, I see colorful tracers, and things that look like ink splotches everywhere. Depending on my mood, I can sometimes see actual objects of varying detail.
Things really get crazy when I’m having a panic attack, when I get derealization, when I’m very tired, or if i’m incredibly sad/depressed.
Plain nothingness here 