It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Zero CC tileable Laminate wood texture, photographed and made by me. CC0
Source Sojan Janso
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Feel free to download and use it, or see the rest of the dark background patterns that I have made. Anyway, I hope you will find something that you like.
Source V. Hartikainen
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin