This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
Prismatic Floral Background No Black
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
The name is totally random, but hey, it sounds good.
Source Atle Mo
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen